The truth is there are no experts in questions of art, as there are, perhaps, in questions of technique. Expert knowledge presupposes the existence of fixed rules, of a canon. There can be no talk of this in the fine arts. The only element of painting that, at least to a certain point—to the point where the individual conception and, with it, really artistic interest first begins—is under objective rules, is drawing, both from its figure as well as its perspective side. This element can be taught, learnt, and faithfully measured, for nature furnishes the scales. On the other hand, the colour element in painting is subject to absolutely no canon, but at best to subjective feeling, at worst to a fashion of the period. Every artificial colour is a convention; for, as I have argued more particularly in my studies of Sisley and Pissarro, none can truly reproduce the real colours of natural phenomena, and it is wholly a consequence of education and habit, when the polychrome of oil-painting or water-colour more easily excites in us the illusion of colouristic truth than the monochrome of the two-colour or of black and white art. One decade paints in dark, another in bright colours. One school likes powerful, another subdued harmonies of colour. Præ-Raphaelites imitate the tone of old frescoes and faded Gobelins. Puvis de Chavannes took the colour out of his pictures by a transparent white-wash, pale as the moon. Besnard, on the contrary, discharges fireworks, without caring in the least if the mad tumults of colour that he loved are possible or not in nature. Carrière envelops his figures in a dense mist. Cottet has, very recently, brought into fashion the black and dark shadings which go right back from Ribot and Prudhon to Velasquez and Ribera. Who is right? Who is wrong? Here everything is feeling, and consequently subjectivity. Of drawing, one can in all cases say (and by photography irrefutably prove), it is correct, or it is wrong. Colour does not admit of a similar verdict. All that can be said of it is: “I like it,” or “I don’t like it.” For beauty in art, in the present condition of the perception theory, the physiology and psychology of pleasurable feelings, there is no other standard than subjective feeling. This is dependent on the greater or the less sensitiveness of the nervous system, on its perceptivity of slight qualitative and quantitative differences in the excitation of the senses, and, therefore, on an essentially congenital constitution of the organism. The gift of receiving strong impressions from works of art can be developed by practice, by the frequent and attentive study of works of art of different kinds; but it cannot be attained artificially by any effort or any amount of study.