Greek Texts & Translations

Of these points some are learnt by experience, some ^note from history, and others by the study of scientific strategy. It is a most excellent thing too that the general should have a personal knowledge both of the roads, and the locality which he has to reach, and its natural features; as well as of the persons by

whom and with whom he is to act. If that is not possible, the next best thing is that he should make careful inquiries and not trust just any one: and men who undertake to act as guides to such places should always deposit security with those whom they are conducting.

These,—and other points like them, it is perhaps possible ^note that leaders may learn sufficiently from the mere study of strategy, whether practical or in books. But scientific investigation requires scientific processes and demonstrations, especially in astronomy and geometry; the working out of which is not much to our present point, though their results are important, and may contribute largely to the success of such undertakings.

The most important operation in astronomy is the calculation of the lengths of the days and nights. If these had been uniform it would not have been a matter requiring any study, but the knowledge would have been common to all the world: since however they not only differ with each other but also with themselves, it is plainly necessary to be acquainted with the increase and diminution of both the one and the other. How can a man calculate a march, and the distance practicable in a day or in a night, if he is unacquainted with the variation of these periods of time? In fact nothing can be done up to time without this knowledge,—it is inevitable otherwise that a man should be sometimes too late and sometimes too soon. And these operations are the only ones in which being too soon is a worse fault than being too late. For the general who overstays the proper hour of action only misses his chance, since he can find out that he has done so before he arrives, and so get off safely: but he that anticipates the hour is detected when he comes up; and so not only misses his immediate aim, but runs a risk of ruining himself altogether.