y your
invincible valour, were glorying in your triumph and victory,--while all
foreign nations were in subjection awaiting your beck and call, and the
Roman people and senate, released from their alarm, were beginning to be
guided by your most noble conceptions and policies, I hardly dared, in
view of your serious employments, to publish my writings and long
considered ideas on architecture, for fear of subjecting myself to your
displeasure by an unseasonable interruption.

2. But when I saw that you were giving your attention not only to the
welfare of society in general and to the establishment of public order,
but also to the providing of public buildings intended for utilitarian
purposes, so that not only should the State have been enriched with
provinces by your means, but that the greatness of its power might
likewise be attended with distinguished authority in its public
buildings, I thought that I ought to take the first opportunity to lay
before you my writings on this theme. For in the first place it was this
subject which made me known to your father, to whom I was devoted on
account of his great qualities. After the council of heaven gave him a
place in the dwellings of immortal life and transferred your father's
power to your hands, my devotion continuing unchanged as I remembered
him inclined me to support you. And so with Marcus Aurelius, Publius
Minidius, and Gnaeus Cornelius, I was ready to supply and repair
ballistae, scorpiones, and other artillery, and I have received rewards
for good service with them. After your first bestowal of these upon me,
you continued to renew them on the recommendation of your sister.

3. Owing to this favour I need have no fear of want to the end of my
life, and being thus laid under obligation I began to write this work
for you, because I saw that you have built and are now building
extensively, and that in future also you will take care that our public
and private buildings shall be worthy to go down to posterity by the
side of your other splendid achievements. I have drawn up definite rules
to enable you, by observing them, to have personal knowledge of the
quality both of existing buildings and of those which are yet to be
constructed. For in the following books I have disclosed all the
principles of the art.

CHAPTER I

THE EDUCATION OF THE ARCHITECT

1. The architect should be equipped with knowledge of many branches of
study and varied kinds of learni