1Cum animadvertissem, imperator, plures de architectura praecepta voluminaque commentariorum non ordinata sed incepta, uti particulas, errabundos1 reliquisse, dignam et utilissimam rem putavi antea disciplinae corpus ad perfectam ordinationem perducere et praescriptas in singulis voluminibus singulorum generum qualitates explicare. Itaque, Caesar, primo volumine tibi de officio eius et quibus eruditum esse rebus architectum oporteat, exposui. Secundo de copiis materiae, e quibus aedificia constituuntur, disputavi; tertio autem de aedium sacrarum dispositionibus et de earum generum varietate quasque et quot2 habeant species earumque 2quae sunt in singulis generibus distributiones. Ex tribus generibus quae subtilissimas haberent proportionibus modulorum quantitates ionici generis moribus, docui; nunc hoc volumine de doricis corinthiisque constitutis (et)3 omnibus dicam eorumque discrimina et proprietates explicabo.
1. When I perceived, your Highness, that many persons had stated the rules of Architecture, and had written commentaries casually, not set in due order but merely inchoate (like atoms) I thought it a worthy and most useful task first of all to reduce the encyclopedia of architecture to a perfect order, and in the several books to explain the qualities1 of the several objects assigned to them. Therefore, Caesar, in the first book I expounded the function of the architect and the subjects in which he should be trained; in the second I discussed the supplies of the materials, of which buildings are constructed; in the third, the arrangements of temples, their different kinds, how many styles of design there were, and the details which belong to them severally. 2. Of the three orders, I taught, in reference to the Ionic order, those rules which, by the use of proportion, furnish the most exact adjustment of the modules. In this book I will proceed to speak of the Doric and Corinthian orders generally, their distinctions and properties.