An observance of this principle makes for homogeneity of design. In reading a book so put together we are spared (without knowing that we are spared) the disturbance of our sense of balance which results, almost without our knowing it, when our eyes fall upon a page some part of which is not "tied in" architecturally with the rest of the book. The effect is similar to that of a many-paneled room with an impost cornice at a certain height in all the panels except two or three where it is either higher or lower. We have, in one case, faulty architecture; in the other, faulty book-making. In judging a book or a building, it should be borne in mind that, however charming its parts, it must be regarded as a whole. If our contemplation of it is to be attended with pleasure and comfort, its parts must be so disposed, so correlated, that they will not produce a "jumpy" effect.
It is not contended that every book in which this refinement of perfectly integrated parts has been ignored should be considered a failure because it is less than perfect. If that were true, few books would pass the test. It would indeed be hypercritical to insist that a failure to observe this principle actually spoils an otherwise well-made book. It is desirable, however, that the principle should be observed _as far as the material will permit_. It must be recognized, also, that sometimes the elements are so diverse--chapter headings or the internal titles of essays, short stories or poems--that a strict adherence to the principle becomes impossible. In such instances, the designer's task is still to strive for order and integration. Perfect order, symmetry, and balance may be unattainable, but this does not justify him in being haphazard. When order is observed we may not be conscious of it; when it is not observed we are aware of its absence. Movement is of the highest importance as a factor of design--such movement, for example, as is imparted to a book by this very diversity of its elements--but good design demands movement that is ordered, not arbitrary. If liberties are taken (and it is desirable, in the interest of vitality and charm, that they should be taken) they must justify themselves aesthetically; they should not only please us in themselves but as evidence of the designer's intelligence, his insight, subtlety, sensitiveness, discrimination, and tact. However diverse the elements or parts of a book may be, however they may, by reason of such diversity, render perfect order and balance impossible, their arrangement should at least possess a _rationale_.