Among wise men, I maintain, the most praiseworthy are they who not only have spoken cleverly on their particular subjects, but have made their assertions good by doing things to match them. Take doctors, for instance: a man of sense, on falling ill, does not send for those who can talk about their profession best, but for those who have trained themselves to accomplish something in it. Likewise a musician who can himself play the lyre and the cithara is better, surely, than one who simply has a good ear for rhythm and harmony. And why need I tell you that the generals who have been rightly judged’ the best were good not only at marshalling their forces and addressing them, but at heading charges and at doughty deeds? Such, we know, were Agamemnon and Achilles of old, Alexander and Pyrrhus more recently.

Why have I said all this? It was not out of an ill-timed desire to air my knowledge of history that I brought it up, but because the same. thing is true of engineers—we ought to admire those who, though famous for knowledge, have yet left to later generations reminders and proofs of their practical skill, for men trained in words alone would better be called wiseacres than wise. Such an engineer we are told, was Archimedes, and also Sostratus of Cnidus, The latter took Memphis for Ptolemy without a siege by turning the river aside and dividing it; the former burned the ships of the enemy by means of his science. And before their time Thales of Miletus, who had promised Croesus to set his army across the Halys dryshod, thanks to his ingenuity brought the river round behind the camp in a single night. Yet he was not an engineer: he was wise, however, and very able at devising plans and grasping problems. . As for the case of Epeius, it is prehistoric: he is said not only to have made the wooden horse for the Achaeans but to have gone into it along with them.