[1] Cum divina tua mens et numen, imperator Caesar, imperio potiretur orbis terrarum invictaque virtute cunctis hostibus stratis triumpho victoriaque tua cives gloriarentur et gentes omnes subactae tuum spectarent nutum populusque Romanus et senatus liberatus timore amplissimis tuis cogitationibus consiliisque gubernaretur, non audebam, tantis occupationibus, de architectura scripta et magnis cogitationibus explicata edere, metuens, ne non apto tempore interpellans subirem tui animi offensionem.

[3] Cum ergo eo beneficio essem obligatus, ut ad exitum vitae non haberem inopiae timorem, haec tibi scribere coepi, quod animadverti multa te aedificavisse et nunc aedificare, reliquo quoque tempore et publicorum et privatorum aedificiorum, pro amplitudine rerum gestarum ut posteris memoriae traderentur curam habiturum. Conscripsi praescriptiones terminatas ut eas adtendens et ante facta et futura qualia sint opera, per te posses nota habere. Namque his voluminibus aperui omnes disciplinae rationes.

1. Whilst, O Cí¦sar, your god-like mind and genius were engaged in acquiring the dominion of the world, your enemies having been all subdued by your unconquerable valour; whilst the citizens were extolling your victories, and the conquered nations were awaiting your nod; whilst the Roman senate and people, freed from alarm, were enjoying the benefit of your opinions and counsel for their governance; I did not presume, at so unfit a period, to trouble you, thus engaged, with my writings on Architecture, lest I should have incurred your displeasure.

2. When, however, I found that your attention, not exclusively devoted to state affairs, was bestowed on the state of the public buildings, so that the republic was not more indebted to you for its extended empire, in the addition of so many provinces, than for your numerous public buildings by which its grandeur is amply manifested, I considered it right that no time should be lost in laying these precepts before you. My reverence for the memory of your virtuous father, to whom I was well known, and from whom, now a participator in council with the gods, the empire descended to you, has been the cause of your good will towards me. Hence, together with M. Aurelius, P. Numisius, and Cn. Cornelius, I have been appointed to, and receive the emoluments arising from the care of, the various engines of war which you assigned to me on the recommendation of your sister.

3. As, through your kindness, I have been thus placed beyond the reach of poverty, I think it right to address this treatise to you; and I feel the more induced to do so from your having built, and being still engaged in the erection of, many edifices. It is proper to deliver down to posterity, as a memorial, some account of these your magnificent works. I have therefore given such definite directions for the conduct of works, that those already executed, as well as those hereafter to be constructed, may be by you well known and understood. In the following pages I have developed all the principles of the art.