of them. As for replacing tiles, roof timbers, and rafters, we need not be so particular about them as about the parts just mentioned, because they can easily be replaced, however defective they may become. Hence, I have shown by what methods the parts which are not considered solid can be rendered durable, and how they are constructed.
9. As for the kind of material to be used, this does not depend upon the architect, for the reason that all kinds of materials are not found in all places alike, as has been shown in the first book. Besides, it depends on the owner whether he desires to build in brick, or rubble work, or dimension stone. Consequently the question of approving any work may be considered under three heads: that is, delicacy of workmanship, sumptuousness, and design. When it appears that a work has been carried out sumptuously, the owner will be the person to be praised for the great outlay which he has authorized; when delicately, the master workman will be approved for his execution; but when proportions and symmetry lend it an imposing effect, then the glory of it will belong to the architect.
10. Such results, however, may very well be brought about when he allows himself to take the advice both of workmen and of laymen. In fact, all kinds of men, and not merely architects, can recognize a good piece of work, but between laymen and the latter there is this difference, that the layman cannot tell what it is to be like without seeing it finished, whereas the architect, as soon as he has formed the conception, and before he begins the work, has a definite idea of the beauty, the convenience, and the propriety that will distinguish it.
I have now described as clearly as I could what I thought necessary for private houses, and how to build them. In the following book I shall treat of the kinds of polished finish employed to make them elegant, and durable without defects to a great age.
