prFinding, O Emperor, that many persons have left us precepts in Architecture, and volumes of commentaries thereon, not systematically arranged, but mere general principles, little more indeed than scattered hints, I considered it a worthy and useful task, first, to give a general view of the whole subject, and then to dilate in each book on the detail. Thus, Cæsar, I treated in the first book on the duties of an architect, and the sciences in which he should be skilled. In the second, I taught the knowledge of the different materials used in building. The third contained instructions on the arrangement of sacred buildings, their different forms and species, and the distributions appropriate to each sort;
2confining myself, however, to the use of the Ionic order, which, of the three, from the great delicacy of its proportions, requires the most attention in its use. I shall now, in this book, point out the difference and properties of the Doric and Corinthian Orders.