‹‹‹ Vitr. 10.16.1 | Table of Contents | Vitr. 10.16.3 ›››
2Whoever, therefore, attends to these precepts, will be able to select from the variety mentioned, and design safely, without further aid, such new schemes as the nature of the places and other circumstances may require. For the defence of a place or army, one cannot give precepts in writing, since the machines which the enemy prepares may not be in consonance with our rules; whence oftentimes their contrivances are foiled by some ready ingenious plan, without the assistance of machines, as was the case with the Rhodians.
2And so, if any one pays attention to these directions, and by selection adapts their various principles to a single structure, he will not be in need of further aids, but will be able, without hesitation, to design such machines as the circumstances or the situations demand. With regard to works of defence, it is not necessary to write, since the enemy do not construct their defences in conformity with our books, but their contrivances are frequently foiled, on the spur of the moment, by some shrewd, hastily conceived plan, without the aid of machines, as is said to have been the experience of the Rhodians.