XXIV. II. Thus far, then, of the place for beauty. We were next to inquire into the characters which fitted it peculiarly for architectural appliance, and into the principles of choice and of arrangement which best regulate the imitation of natural forms in which it consists. The full answering of these questions would be a treatise on the art of design: I intend only to say a few words respecting the two conditions of that art which are essentially architectural,--Proportion and Abstraction. Neither of these qualities is necessary, to the same extent, in other fields of design. The sense of proportion is, by the landscape painter, frequently sacrificed to character and accident; the power of abstraction to that of complete realisation. The flowers of his foreground must often be unmeasured in their quantity, loose in their arrangement: what is calculated, either in quantity or disposition, must be artfully concealed. That calculation is by the architect to be prominently exhibited. So the abstraction of few characteristics out of many is shown only in the painter's sketch; in his finished work it is concealed or lost in completion. Architecture, on the contrary, delights in Abstraction and fears to complete her forms. Proportion and Abstraction, then, are the two especial marks of architectural design as distinguished from all other. Sculpture must have them in inferior degrees; leaning, on the one hand, to an architectural manner, when it is usually greatest (becoming, indeed, a part of Architecture), and, on the other, to a pictorial manner, when it is apt to lose its dignity, and sink into mere ingenious carving. XXV. Now, of Proportion so much has been written, that I believe the only facts which are of practical use have been overwhelmed and kept out of sight by vain accumulations of particular instances and estimates. Proportions are as infinite (and that in all kinds of things, as severally in colors, lines, shades, lights, and forms) as possible airs in music: and it is just as rational an attempt to teach a young architect how to proportion truly and well by calculating for him the proportions of fine works, as it would be to teach him to compose melodies by calculating the mathematical relations of the notes in Beethoven's Adelaïde or Mozart's Requiem. The man who has eye and intellect will invent beautiful proportions, and cannot help it; but he can no more tell _us_ how to do it than Wordsworth could tell us how to write a sonnet, or than Scott could have told us how to plan a romance. But there are one or two general laws which can be told: they are of no use, indeed, except as preventives of gross mistake, but they are so far worth telling and remembering; and the more so because, in the discussion of the subtle laws of proportion (which will never be either numbered or known), architects are perpetually forgetting and transgressing the very simplest of its necessities.