It may not be out of order to say at this point that, while a considerable range in the size of books is not only permissible but desirable, there are limits at both ends of the scale where practicability ceases to exist and we pass into the realm of curiosities and _tours de force_. Thus the miniature book, for all its charm, lies outside the confines of normal book-design. As to the maximum size that may be legitimately allowed for a book, it should never, I think, exceed the normal folio height (defined approximately by the larger moulds employed for manufacturing hand-made paper) while its bulk and weight should not preclude the possibility of holding it by the spine with one hand while turning the leaves with the other, when such a method of referring to its contents may be necessary. And now a final word as to dimensions. Large or small, the most perfect book will always be one of which the thickness bears a just and agreeable relation to its height and width. Small and slender books are delightful objects which no one could wish to abolish (one cannot say as much for the lamelliform folio, a veritable atrocity), but their inferiority to books of a meet thickness becomes apparent when, with (or, worse yet, without) their vertical, neck-twisting titles they are placed on a shelf.
We must next turn our attention to those aspects of a book which have to do with its plan and construction and which we have called _tectonic_.
In its physical character a book addresses itself to two of our senses, the sense of sight and the sense of touch. Because the tactile qualities of a book are relatively of less importance than its visual aspects, let us first deal with those elements which are, in part at least, evaluated through the sense of touch.
Our first impression of a book is received from its exterior, its binding. Now the qualities to be looked for in the binding of a book are: (1) the character and quality of the material, (2) suitability, (3) soundness and charm of design, (4) agreeable color (a relative term), (5) workmanship, (6) pleasantness to the touch. Granting adequacy in all of these (and no book can pretend to fineness without such adequacy), there is still another _desideratum_ less easy to specify. It might be called (7) "the evidence of durability." A book when taken in the hand should have a feeling of compactness, almost of solidity. I do not mean by this that it should feel like a block of wood, but it should, when picked up, when opened, or when its hinges are tested, give the impression that leaves and cover are so firmly (and honestly) knit together that they constitute a unit, having in its "feel" the evidence (or the assurance) of durability.