Many of you looking at this immensely long diatribe may see this as convincing proof of my loss of mind. That might be true. But I would encourage those inclined to think this way to skip over this vastly overlong piece on the art of Impressionism. I was not intending to do this. Something made me do it.

When I looked at my photographs of various paintings at the Louvre and then at the Musée d’Orsay I had a vague recollection of reading about Impressionism years ago. I am talking about 30 years ago. I dusted off old art books from my bookshelf and got engrossed all over again. I read lengthy passages and tried to tie them to the paintings we had seen that day in Paris. I felt compelled to write these thoughts down based on that reading. I am no expert on art and do not claim to be. Yet for some reason these thoughts and vague recollections were floating around my brain and I had to try to organize them. This is the result. Like Dylan once said, its all just “worthless foam from the mouth.” Please do not feel compelled to read any of this unless you must.

So based on the better part of a day in 2 of the greatest art museums in the world and my re-reading of old texts on art, mixed up with some equally vague thoughts about philosophy as well to create a veritable strange brew, I set my thoughts down. For what very little they are no doubt worth.

Impressionism is often considered the starting point for modern art. This art movement began in France and many of its practitioners were French. It is a quintessential French art tradition. Though it certainly did not start out as traditional. Far from it in fact. It was reviled at first.

In Paris in the middle of the 19^th century the École des Beaux-Arts (School of Fine Arts) was considered the centre of the world. It was one of many influential arts schools in France. In those days there were many written and unwritten laws of French art and life. Compliance with those rules was an absolute necessity if an artist wanted to achieve “success.” Art was a career in France. In fact in France it was one of the most important careers. In France art was not as important as life, it was much more important than that.

In France in many ways the life of an artist was comparable to a military career. It was governed just as strictly by rules that had to be followed scrupulously in order to advance. In the end the rewards were impressive. Many artists eventually achieved wealth, status and social standing after following those rules diligently for a lifetime.

The Academy of Fine Arts (particularly the Institut de France) governed the arts like the dictator of a banana republic. It was pure enlightened despotism. From the Academy the leaders and teachers of art were chosen to lead the next generation of artists. The Academy also controlled the jury admissions and rewards for the biennial Salons. This gave them the power to exclude from the exhibitions any artist who did not respectfully comply with their requirements.

The Director of the Academy also participated in decision making for various museums in the selection of art for purchase or earlier for acquisitions by the Emperor. They also strongly influenced the awarding of commissions for the production of new art in various institutions, both governmental and private. As John Rewald explained, “In all these questions the Academy naturally favored its most docile pupils, who in turn were favored by that public which sees in medals and prizes the proof of an artist’s talent.” ^[1]

It is true that the school now located on the Left Bank across the Seine from the Louvre had an astonishing history of 350 years during which it trained some of the greatest artists in Europe. Its style was “classical.” That was a great style modeled on the classical antiquities from Greece and Rome and it helped to preserve those idealized forms and to pass that style on to future generations. It was a vital institution, but like so many vital institutions it became encrusted with routine, rules, and dogma. We know many institutions in which the same thing happened. As a result by the middle of the 19^th century it had earned its revolution. And it got one. The revolution was delivered by the so-called impressionists.

The artistic style that guided the Academy at the time was that put forth by Jean-Jacque David, whose painting we had admired at length in the morning. David lived from 1748 to 1825. He was a painter of the Neoclassical style and was widely considered the preeminent painter of his time. His cerebral brand of history painting marked a change away from Rococo frivolity that many were starting to lose their taste for. A the time this was fresh change in art. It was revolutionary at the time. It was a return to the classics. This style was known for classical austerity and severity and heightened feeling that harmonized with the moral climate of the final years of the Ancient Regime that met its defeat in the French Revolution.

David actually later came to become a supporter of the revolution and was even appointed by Robespierre as a virtual artistic dictator under the French Republic. He was imprisoned by Robespierre and later changed his allegiance to Napoleon. David had a large number of pupils and became the artist with the strongest influence on the art of the 19^th century. In particular he was the darling of the Salons of Paris.

David’s most famous student at the Academy was Jean Dominique Ingres. In 1855 Camille Pissaro from St. Thomas in the West Indies came to see the great Exposition Universelle in Paris. This was the first exhibition to include a large contingent of international art. This huge exhibition was the product of France wanting to show the world how great it was. Art was shown from 28 countries and someone said it was the greatest collection of paintings and sculpture ever gathered in one building at one time. France’s share of art was of course by far the largest.

Artists were chosen for that exhibition with more care than they normally were because so many international artists and critics and connoisseurs would see the collection. After all the French artists would have to compare favorably with artists from around the world. Delacroix for example, whose art we had also admired in the morning at the Louvre, had chosen for display some of his finest works.

Ingres had actually refused to send works for past 20 years because he felt he had been slighted. He was big enough that he could afford to do that. But for this magnificent exhibition he made an exception. It did not hurt that the government had promised him special honours.

Ingres had advised young painters to copy their models stupidly. [2] He said that an object well drawn is always well enough painted. Ingres always emphasized line over color. As a result many of his followers thought of paintings as “colored drawings.” Ingres and his group considered as ‘badly drawn’ landscapes of Corot or the composition of Delacroix because in these every object was not carefully delineated by a minute contour. To Ingres’ pupils correct drawing finally became an end in itself, and a ‘noble contour’ was a sufficient excuse for a lack of inspiration, dry execution, and dull colouring. In the absence of any personal link with the classical ideals admired by their master, they simply blended with the classical tradition with cheap genre style. It was this mixture of empty craftsmanship with anecdotal platitude, that, at the Salons caused the delight of the picture-reading public…Yet, as Delacroix put it, their works did not contain that “dash of truth, the truth which comes from the soul.” [3] 

It is interesting that even Ingres “frankly admitted that the Salon stifles and corrupts the feeling for the great, the beautiful; artists are driven to exhibit there by the attractions of profit…Thus the Salon is literally no more than a picture shop, a bazaar in which the tremendous number of objects is overwhelming, and business rules instead of art.” [4] Of course this has always been the problem with art—its unholy union with business that all too often brings forth monsters from the deep. Monsters that many nonetheless clamour for, like braying donkeys of idiocy. Many others since then have laid similar charges. For example, Walter Januszcjak one of the first art critics I started to read when I first subscribed to the Guardian in 1982 said, “the art world has become an industry supplying spiritual knick-knacks to the rich.”

Pissaro who later became one of the leaders of the Impressionist movement, was a bit mystified by the exhibition. For one thing, he noticed that great variety of styles. He was also puzzled at how little space was given to some painters, in comparison to Delacroix and Ingres, even though he felt they were outstanding too. These included Corot, Daubigny, who were early Impressionist. Others were entirely excluded and Pissaro could not understand it. A number of canvases now considered masterpieces were rejected or refused.

The men and women who became the Impressionists were the rebels against the calcifying Academy and its Salons. Unlike Ingres, they refused to comply with the requirements of the Salons. They were accused of producing ugly art because it did not conform to the rules of the Salon. So they revelled in that. As one of the artists Denoyers proclaimed, “Let’s be a little ourselves, even though we might be ugly…Let’s not write, not paint anything except what is, or at least what we see, what we know, what we have lived. Don’t let us have any master nor pupils! A curious school it is, don’t you think, where there is neither master nor student, and whose only principles are independence, sincerity, individualism.” [5]  The rebels were excluded from the Salons but not the cafés of Paris. Rewald described those boisterous cafés like this;

 

The noisy atmosphere of these cafés, where idols were created or demolished within a few minutes, where no title to glory was well enough earned to prevent insults, where logic was often replaced by vehemence and comprehension by enthusiasm—this atmosphere was in violent contrast to that of the official art circles. Here, were life and tremendous will to conquer, and even if many erred or exaggerated, there was in their fight against prejudice and tradition a positive element, the desire to prove the value of new beliefs through the quality of new works. Pissarro’s often proclaimed opinion that the Louvre ought to be burned may well of had its root in these discussions where the heritage of the past was considered harmful for those who wanted to build a world of their own. [6]

In 1863 the jury was even more extreme in its refusals owing to the intransigence of some of its members. Many artists were turned down, like Manet. Many of those artists complained to the Emperor. They took their art seriously in France at that time. Napoleon III declared that he would arrange for another exhibit for those who had been refused by the jury. All artists would be welcomed. All they had to do was apply. It was called the Salon des Refuses, the “most rejected of the rejected.” One artist proudly proclaimed that he had been refused on moral grounds.

Of course many members of the public thought these artists who had been refused were refused because their art was inferiors and they were only complainers. Many members of the public mocked the refused artists, as whining losers. Yet these young artists were not to be stopped.   One of the critics noted that Manet demonstrated that he was very “sensitive to intense impressions.” Many members of the public though saw his art as vulgar. That was partly because of his revolutionary techniques.

It may be doubted whether Manet’s paintings would have provoked such criticism had it not been painted in broad contrasts and frank opposition, with a tendency to simplification. His “vulgarity”, in the eyes of the public, lay probably even more in in his execution than in his subject matter. It was his renunciation of the customary slick brushwork, his fashion of summarily indicating background details and of obtaining forms without the help of lines, by opposing colors or sketching his contours, if necessary with decisive brushstrokes in color (which helped to model volumes instead of limiting them), that were responsible for the almost universal disapproval he met. [7] 

One of the critics called the Salon des Refuses “a war on beauty.” [8] Future Salons generated similar refusals, though not total rejections. Some of the artists were permitted a few exhibits only. Some of their colleagues reacted badly when someone like Manet exhibited one painting at the official exhibit in 1874.

The artists had little respect for the bourgeois audiences who they believed did not understand art even though they did not mock all the paintings.

Years later Zola was to describe in a novel the atmosphere of an exhibition resounding with the guffaws of curiosity-seekers: “These laughs were no longer smothered by their handkerchiefs of the ladies, and the men distended their bellies the better to give vent to them. It was the contagious mirth of a crowd which had come for entertainment, was becoming excited by degrees, exploded apropos of nothing, and was enlivened as much by beautiful things as by execrable ones… They nudged each other, the doubled up… every canvas had its appreciation, people called each over to point out a good one, witty remarks were constantly being passed from mouth to mouth… expressing the sum of asininity , of absurd commentary, of bad and stupid ridicule that an original work can evoke from bourgeois imbecility. [9] 

In 1874 Monet, Renoir, Cezanne, Pissarro and others launched an exhibit on their own. They were the young rebels of Paris. Like existentialism, they did not have a coherent program. They painted train stations, cafés, gardens, and surprisingly to me, places of industry. They did not ignore the modern world; they challenged it.

After that exhibit an influential Parisian art critic was highly critical of their work. He said it was often incomplete, and sketch-like. He ridiculed it calling their art “impressions.” So the term at first was an insult. Eventually the artists adopted the name, just as Hillary Clinton hater adopted the term “Adorable deplorables.” People who are insulted like to do nothing more than turn the tables on their tormentors.

Eventually people realized that it take great skill to render an image not as a sharp reproduction, but an “impression.” This was the beginning of the movement to sever the umbilical connection of art to representation. For the first time, artists realized that it was not necessary to present an accurate representation of the world. This was the precursor of modern art. They captured its imperfections. This is one of the things I like about the Impressionists. They embraced imperfections realizing that the ideal was not real.

Monet and Renoir, two of the leaders of the Impressionist movement did not deny that they painted in a rough manner. Both made extensive use of vivid brush strokes. They also used a technique with rapid strokes, dots and commas (strokes in the brief swirl of a comma) to capture glistening atmosphere. As Rewald said, “what officials would have considered “sketchiness”—the execution of an entire canvas without a single definite line, the use of the brushstroke as a graphic means, the manner of composing surfaces wholly through small particles of pigment in different shades—all this now because for Monet and Renoir not merely a practical method of realizing their intentions, it became a necessity if they were to retain the vibrations of light and water, the impression of action and life. Their technique was the logical result of their work out-of-doors and their efforts to see in subjects not the details they recognized bu8t the whole they perceived.” [10]

Stéphane Mallarmé who wrote a monthly article for the Art Monthly probably understood the originality of the Impressionists better than most. He wrote about the movement this way,

As no artist has on his palette a transparent and neutral color answering to open air, the desired effect can only be obtained by lightness or heaviness of touch, or by the regulation of tone. Now Monet and his school use simple color, fresh, or lightly laid on, and their results appear to have been attained at the first stroke, that the ever-present light blends with and vivifies all things. As to the details of the picture, nothing should be absolutely fixed in order that we may feel that the bright gleam which lights the picture, or the diaphanous shadow which veils it, are only seen in passing, and just when the spectator beholds the represented subject, which being composed of a harmony of reflected and ever-changing lights, cannot be supposed always to look the same but palpitates with movement and light, and life… That which I preserve through the power of Impressionism is not the material portion, which already exists, superior to any mere representation of it but the delight of having recreated nature touch by touch. I leave the massive and tangible solidity to its fitter exponent, sculpture,. I content myself with reflecting on the clear and durable mirror of painting, that which perpetually lives yet dies every moment, which only exists by will of Idea, yet constitutes in my domain the only authentic and certain merit of nature—the Aspect. [11]

According to the perceptive art critic, Jules Antoine Castagnary, who spent a lot of time with the Impressionists and learned a lot from them,

 

The common concept which united them as a group and gives them a collective strength in the midst of our disaggregate epoch is the determination not to search for a smooth execution, but to be satisfied with a certain general aspect. Once the impression is captured, they declare their role terminated…If one wants to characterize them with a single word that explains their efforts, one would have to create the new term of Impressionists. They are impressionists in the sense that they render not a landscape but the sensation produced by a landscape. [12]

 

I really believe that this describes their technique as well as anything. It reminds me of those who reject perfection. They give up before perfection has been achieved. Perfection is not necessary. It may in fact be opposed to the goal of the artist.

As a result the artists came to accept the designation of “Impressionist” that started out as a term of ridicule. Of course, some of the artists denied that they were part of the group. Artists are an unruly lot. That’s one of the reasons they are so loveable. The name was interesting, as Rewald said,

 

The term “impressionism,” coined in derision, was soon to be accepted by the friends. In spite of Renoir’s aversion to anything that might give them the appearance of constituting a new ‘school’ of painting, in spite of Degas’ unwillingness to admit the designation with regard to himself, and in spite of Zola’s persistence in calling the painters ‘naturalists,’ the new word was there to stay. Charged with ridicule and vague as it was, ‘impressionism’ seemed as good a term as any other to underline the common element in their efforts. No one word could be expected to define with precision the tendencies of a group of men who place their own sensations above any artistic program. Yet whatever meaning the word might have had originally, its true sense was to be formulated not by critics but by the painters themselves. Thus it was that from among their midst—and doubtless with their consent—came the first definition of the term. It was one of Renoir’s friends who proposed it, writing a little later: ‘Treating a subject in terms of the tone and not of the subject itself, this is what distinguishes the impressionists from other painters.”[13]

It is also noteworthy that the essence of the painting was no longer “the subject itself,” but rather its tone. That harkens out to a subsequent movement in art—abstraction that deep-sixed the very subject entirely concentrating entirely on tones. It would not take long and representation in art would be superseded. The Impressionists had liberated themselves from traditional principles of art and traditional subjects of art. The group was known for its “intense sensibilities,” [14] as Rewald called their skills. And they employed those sensibilities to lead to a revolution in art that was as extreme as any change in the history of art. As Rewald said, “And in doing so they had openly renounced even the recreating reality. Rejecting the objectivity of realism, they had selected one element from reality—light—to interpret all of nature.” [15]

So the Impressionists found a new subject their own impression of light. I believe that one of the paintings we saw today illustrated that as much as any. This was Claude Monet’s sensational painting of the English Parliament that he painted in 1904. It has just the most vague outline of Parliament but the glory of the painting is the light of the sunset (or sunrise) and its reflection in the Thames. I did not realize it but a couple of days later I photographed more or less the same image. But the wonder of the painting is the wonder of the light. There is only a hint of a subject beyond that. The light is all. And light, as the Gothic Architects realized, is divine.

Of course painting light is never easy. In England that genius John M. W. Turner had tried to that with astounding skill and bravery. Turner was a Romantic who followed the lead of the English romantic poets like Wordsworth, Byron, Shelley, and Keats. These poets emotionalized nature. As Helen Gardner said, “These poets, interested in describing nature’s looks, and moods, read the natural landscape closely and sympathetically, until they came to see it almost as a projection of themselves; in a word, they subjectivized it.” [16]

This reminds me of what Northrop Frye said, “ the poet’s job (he could have said the artist’s job) is not to describe nature, but to show you a world completely absorbed and possessed by the human mind.” [17] In the same book, Frye said, “The poet too is an identifier, everything he sees in nature he identifies with human life.” [18] Literature, like all art, according to Frye is doing the work that mythology does—it gives the world a human face. “There’s a difference between the world you’re living in and the world you want to live in. The world you want to live in is a human world, not an objective one.”[19]

So Turner expanded the role of light “greatly increasing the role of pure color…in his later paintings he increasingly reveals his awareness that color and light are so closely related as to be the same, and he brings his art to a point where it foreshadows Impressionism.”[20] John Constable continued this trend in English art, but it took the Impressionist to bring it to a spectacular conclusion.

Rewald, an acknowledge expert on the art of the Impressionists has a lengthy explanation of the group. As he reported,

 

Their new approach to nature had prompted the painters gradually to establish a new palette and create a new technique appropriate to their endeavour to retain the fluid play of light. The careful observation of colored light appearing in a scene at a particular moment and led them to do away with the traditional dark shadows and to adopt light pigments. It also led them to ignore local colors, subordinating the abstract notion of local tones to the general atmospheric effect. By applying their paint in perceptible strokes, they had succeeded in in blurring the outlines of objects and merging them with the surroundings. This method had further permitted introducing one color easily into the area of another without degrading or losing it, and thus enriching the color effects. But, above all, the multitude of obvious touches and the contrasts among them had helped to express or suggest the activity, the scintillation of light, and to recreate it to a certain extent on canvas. Moreover, the technique of vivid strokes seemed best suited to their efforts to retain rapidly changing aspects. Since the hand is slower than the eye, which is quick to perceive instantaneous effects, a technique to permit the painters to work rapidly was essential if they were to keep pace with their perception. Alluding to these problems, Renoir used to say, “out-of-doors is always cheating.” Yet their cheating merely consisted in making a choice among the multitude aspects which nature offered., in order to translate the miracles of light into a language of pigment and two dimensions, and also to render the chose aspect with the color and the execution that came closest to their impression. [21] 

I really believe this sums up Impressionism as well as can be done with the puny power of words.

Like the existentialists that followed them, in time and in spirit, the Impressionists tried to capture the moment—here and now. They tried to reveal a personal and subjective impression of the fleeting world of moments. As a result their brushwork was often rapid and visible. They saw the moment as more real than the duration. Here and now is all. As Baudelaire said, “Modernity is the transitory, the fugitive, the contingent, one half of art of which the other half is the eternal and the immutable…This transitory, fugitive element, the metamorphoses of which are so frequent, you have no right to despise or do without. By suppressing it you forcibly tumble into the emptiness of an abstract and undefinable beauty.” [22]

The French art critic Odilon Redon perceptively recognized this important aspect of the Impressionists. As he said of, Corot, “He is the painter of a moment, of an impression.” [23]

Impressionists often were inspired to paint by the sea, or ponds, or rivers. Antonin Proust said this about an important French painter, “Courbet once gave a superb reply when Daubigny complimented him on a study of the sea. ‘This is not a study of the sea,’ he said, it represents an hour.’ That is what people do not sufficiently understand, that one does not paint a landscape, a seascape, a figure—one paints an impression of an hour.” [24] That is what Impressionism is all about.

Existentialism the quintessential philosophy of the early twentieth century had the same focus. The here and now was its concern.

Degas understood this. He had been deeply affected by a long passage from a novel by the Goncourt brothers Manette Saloman in which one of the main characters give a long soliloquy in which he expressed the credo of the authors of the book,

 

All ages carry within themselves a Beauty of some kind or other, more or less close to the earth, capable of being grasped and exploited—It is a question of excavation—It is possible that the Beauty of today may be covered, buried, concentrated—to find it there is perhaps need of analysis, a magnifying glass near-sighted vision, new psychological processes.—The question of what is modern is considered exhausted, because there was this caricature of truth in our time, something to stun the bourgeoisie: realism!—because one gentleman created a religion out of the stupidly ugly, or the vulgar ill assembled and without selection, of the modern—but common without character, without expression, lacking what is beauty and the life of the ugly in nature and in art: style! The feeling the intuition for the contemporary, for the scene that rubs modern shoulders for you, for the present in which you sense the trembling of your emotions and something of yourself—everything is there for the artist. The nineteenth century not produce a painter!—but that is inconceivable—A century that has endured so much, the great century of scientific restlessness and anxiety for the truth—There must be found a line that would precisely render life, embrace from close at hand the individual , the particular, a living, human inward line in which there would be something of a modelling by Houdon, a preliminary pastel sketch by La Tour, a stroke by Gavarni—A drawing truer than all drawing—a drawing—more human. [25]

 

The Impressionists loved the atmospheric conditions that they found about them outdoors. As a result their images are often very light—the very color of light. The framing is often off centre. Photographers later used the same technique. They call it ‘the rule of thirds.’ They don’t like things in dead centre as to them the image feels dead that way. Photographers learned this from Impressionists whether they realize it or not.

For the first few years the Impressionists were very poor. The critics largely rejected their work, as did people. At first. In time the critics and public both came to appreciate them. In fact, eventually their art sold for millions. In my opinion that is as absurd as paying them nothing.

The Impressionists also had important insights for what I have called the philosophy of affinity. This is the philosophy of Indigenous peoples of North America in particular. It is a philosophy towards which I am very sympathetic. It holds that all life on earth is connected. We are a part of the world. We are embedded in it. We are not separate from it.

The European version of this philosophy was enunciated (sort of) by Martin Heidegger who used the interesting concept of everything that exists is being-in-the-world to use an apt phrase from Martin Heidegger.

It is also interesting to me at least, that this philosophy is implicit in the views of Northrop Frye.

Rewald talked about water in the art of the Impressionists. This is what Rewald said on that subject,

 

The subject of water played an important role in the development of the style of Monet and his friends. In 1868 Monet painted a picture of a woman seated on a riverbank in which the reflections on the water became one of the main features. Just as snow scenes had permitted the artists to investigate the problem of shadows, the rendering of water offered an excellent opportunity to observe reverberations and reflections. Thus they could further develop their knowledge of the fact that so-called local color was actually a pure convention and that every object presents to the eye a scheme of colors derived from its proper hue, from its surroundings, and from atmospheric conditions. Moreover, the study of water gave pretext for the representation of formless masses livened only by the richness of nuances, of surfaces, whose texture invited vivid brushstrokes. [26]

 

Monet had discovered that these so-called local colors varied according to their surroundings and this was a decisive step in art and not only that was “a decisive step toward the full understanding of nature.” [27] That means, I believe, a full understanding that everything is connected. As John Muir said, “When one tugs at a single thing in nature, one finds it attached to everything.” This is an understanding derived from art. Not just philosophy.

 

 

[1] John Rewald, The History of Impressionism, (1973) p. 19

[2] John Rewald, The History of Impressionism, (1973) p. 20

[3] John Rewald, The History of Impressionism, (1973) p. 20

[4] quoted by John Rewald, The History of Impressionism, (1973) p. 20

[5] quoted by John Rewald, The History of Impressionism, (1973) p. 28

[6] John Rewald, The History of Impressionism, (1973) p. 29-30

[7] John Rewald, The History of Impressionism, (1973) p. 86

[8] John Rewald, The History of Impressionism, (1973) p. 326

[9] John Rewald, The History of Impressionism, (1973) p. 328

[10] John Rewald, The History of Impressionism, (1973) p. 230

[11] John Rewald, The History of Impressionism, (1973) p. 372

[12] John Rewald, The History of Impressionism, (1973) p. 330

[13] John Rewald, The History of Impressionism, (1973) p. 338

[14] John Rewald, The History of Impressionism, (1973) p. 338

[15] John Rewald, The History of Impressionism, (1973) p. 338

[16] Helen Gardner, Art Through the Ages, (1975) p. 684

[17] Northrop Frye, The Educated Imagination, (1963) p. 11

[18] Northrop Frye, The Educated Imagination, (1963) p. 31

[19] Northrop Frye, The Educated Imagination, (1963) p. 4

[20] Helen Gardner, Art Through the Ages, (1975) p. 684

[21] John Rewald, The History of Impressionism, (1973) p. 338

[22] quoted in John Rewald, The History of Impressionism, (1973) p. 128,

[23] quoted in John Rewald, The History of Impressionism, (1973) p. 188

[24] quoted in John Rewald, The History of Impressionism, (1973) p. 224

[25] John Rewald, The History of Impressionism, (1973) p. 174

[26] John Rewald, The History of Impressionism, (1973) p. 228

[27] John Rewald, The History of Impressionism, (1973) p. 116