One who enters a picture-gallery, or who reads a series of poems, having looked and read, may go further: he may seek out the nature and the relations of the things there expressed. Thus those pictures and compositions, each of which is an individual inexpressible in logical terms, are gradually resolved into universals and abstractions, such as _costumes, landscapes, portraits, domestic life, battles, animals, flowers, fruit, seascapes, lakes, deserts; tragic, comic, pathetic, cruel, lyrical, epic, dramatic, chivalrous, idyllic facts,_ and the like. They are often also resolved into merely quantitative categories, such as _miniature, picture, statuette, group, madrigal, ballad, sonnet, sonnet-sequence, poetry, poem, story, romance,_ and the like. When we think the concept _domestic life,_ or _chivalry,_ or _idyll,_ or _cruelty,_ or one of the quantitative concepts mentioned above, the individual expressive fact from which we started has been abandoned. From æsthetes that we were, we have changed into logicians; from contemplators of expression, into reasoners. Certainly no objection can be made to such a process. In what other way could science arise, which, if it have æsthetic expressions presupposed in it, must yet go beyond them in order to fulfil its function? The logical or scientific form, as such, excludes the æsthetic form. He who begins to think scientifically has already ceased to contemplate æsthetically; although his thought assumes of necessity in its turn an æsthetic form, as has already been said, and as it would be superfluous to repeat. Error begins when we try to deduce the expression from the concept, and to find in what takes its place the laws of the thing whose place is taken; when the difference between the second and the first step has not been observed, and when, in consequence, we declare that we are standing on the first step, when we are really standing on the second. This error is known as the _theory of artistic and literary kinds._ "What is the _æsthetic_ form of domestic life, of chivalry, of the idyll, of cruelty, and so forth? How should these contents be _represented_?" Such is the absurd problem implied in the theory of artistic and literary classes, when it has been shorn of excrescences and reduced to a simple formula. It is in this that consists all search after laws or rules of classes. Domestic life, chivalry, idyll, cruelty and the like, are not impressions, but concepts. They are not contents, but logical-æsthetic forms. You cannot express the form, for it is already itself expression. For what are the words cruelty, idyll, chivalry, domestic life, and so on, but the expression of those concepts?