The science of Mechanics, Hermodorus my son, in so far as it is useful in many great affairs of men, has become a worthy subject for philosophers' interest and a worthy object of aspiration for all those concerning themselves with the mathematical sciences. This is because this science is almost the first to approach knowledge of the nature of the matter of what is in the world. For, since the stability and decay of bodies together with their movements, fall into the category of universals, this science establishes with reasons such of them as are in their natural state, and compels some of them to move from the natural places peculiar to them, imparting to them movements contrary to their own by means of the devices which lie within its scope, and which are reached through ideas derived from matter itself.

Some of Heron's followers who have studied the science of mechanics have stated that this is in part theoretical and in part practical the former being derived from geometry, arithmetic, astronomy, and the natural sciences, while the latter is brought to perfection through the technique of blacksmiths and coppersmiths, builders, carpenters and sculptors, and their skill and subtlety in their work.

A man who had studied the sciences which we have just listed since his youth and had become expert in knowledge of the crafts which we have mentioned, and having in addition an excellent mobility in his nature, would, according to these people, excel in finding out mechanical contrivances, and he it was whom they used to call "chief-artificer". But those who were unable to combine these many sciences and crafts which we have mentioned were advised, if they wanted to do some work on mechanics, to learn the craft needed in that operation and appropriate to it.