§9.15.1κρατεῖ δʼ ἐπὶ πάντων μὲν τῶν ἀνθρωπείων ἔργων ὁ καιρός, μάλιστα δὲ τῶν πολεμικῶν.
Opportunity rules over all human undertakings, and most of all those of war.
§9.15.2διὸ προχείρως ἰστέον τῷ στρατηγῷ τροπὰς ἡλίου θερινὰς καὶ χειμερινάς, ἔτι δʼ ἰσημερίας καὶ τὰς μεταξὺ τούτων αὐξήσεις καὶ μειώσεις ἡμερῶν καὶ νυκτῶν· §9.15.3οὕτως γὰρ ἂν μόνως δύναιτο συμμετρεῖσθαι πρὸς λόγον τὰ διανύσματα καὶ κατὰ γῆν καὶ κατὰ θάλατταν.
Therefore, the general must have ready at hand knowledge of the summer and winter solstices, and further of the equinoxes, and the increases and decreases of days and nights between them; for only in this way could he calculate proportionally the distances to be traversed both by land and by sea.
§9.15.4καὶ μὴν τοὺς κατὰ μέρος καιροὺς ἀναγκαῖον εἰδέναι, καὶ τοὺς τῆς ἡμέρας καὶ τοὺς τῆς νυκτός, πρὸς τὸ γινώσκειν πηνίκα ποιητέον καὶ τὰς ἐξεγέρσεις καὶ τὰς ἀναζυγάς· §9.15.5οὐ γὰρ οἷόν τε τοῦ τέλους τυγχάνειν μὴ οὐ τῆς ἀρχῆς εὐστοχήσαντα.
Moreover, it is necessary to know the detailed divisions of time, both of the day and of the night, in order to know at what hour one must order both the reveille and the departure; for it is not possible to attain the end without having hit upon the right beginning.
§9.15.6τοὺς μὲν οὖν τῆς ἡμέρας καιροὺς τῇ σκιᾷ θεωρεῖν οὐκ ἀδύνατον, ἔτι δὲ τῇ κατὰ τὸν ἥλιον πορείᾳ καὶ τοῖς ἐπὶ τοῦ κόσμου γινομένοις αὐτοῦ τούτου διαστήμασι· §9.15.7τοὺς δὲ τῆς νυκτὸς δυσχερές, ἐὰν μή τις ἐπὶ τοῦ φαινομένου τῇ τῶν δώδεκα ζῳδίων οἰκονομίᾳ καὶ τάξει συμπεριφέρηται· πάνυ δὲ καὶ τοῦτο ῥᾴδιον τοῖς τὰ φαινόμενα πεπολυπραγμονηκόσιν.
Now, it is not impossible to observe the hours of the day by the shadow, and further by the course of the sun and the intervals of this same body on the celestial sphere; but those of the night are difficult, unless one is familiar with the arrangement and order of the twelve signs of the zodiac on the celestial sphere; yet this too is very easy for those who have studied the heavenly phenomena.
§9.15.8ἐπεὶ γὰρ ἀνίσων οὐσῶν τῶν νυκτῶν ὅμως ἐν πάσῃ τῇ νυκτὶ τῶν δώδεκα ζῳδίων ἓξ ἀναφέρεσθαι συμβαίνει, φανερὸν ὡς ἀναγκαῖον ἐν τοῖς αὐτοῖς μέρεσι πάσης νυκτὸς ἴσα μέρη τῶν δώδεκα ζῳδίων ἀναφέρεσθαι.
For since, though the nights are unequal, it always happens that six of the twelve signs rise in the course of every night, it is clear that in the proportional parts of any night equal parts of the twelve signs must rise.
§9.15.9τοῦ δʼ ἡλίου γνωριζομένου καθʼ ἡμέραν, ποίαν μοῖραν ἐπέχει, δῆλον ὡς δύναντος τούτου τὴν κατὰ διάμετρον ἐπιτέλλειν ἀνάγκη.
And since it is known during the day which degree of the zodiac the sun occupies, it is clear that when the sun sets, the point diametrically opposite to it must rise.
§9.15.10λοιπὸν ὅσον ἂν τὸ μετὰ ταύτην μέρος ἀνατεταλκὸς φαίνηται τοῦ ζῳδιακοῦ, τοσοῦτον εἰκὸς ἠνύσθαι τῆς νυκτὸς αἰεί.
Consequently, in proportion as the part of the zodiac rising after this point appears, so much of the night must always be expected to have passed.
§9.15.11γνωριζομένων δὲ τῶν ζῳδίων καὶ κατὰ τὸ πλῆθος καὶ κατὰ τὸ μέγεθος, τοιούτους γίνεσθαι μετὰ ταῦτα συμβαίνει καὶ τοὺς κατὰ μέρος καιροὺς τῆς νυκτός.
And if the signs of the zodiac are known both in number and in size, it follows that the detailed divisions of the night also become known accordingly.
§9.15.12ἐν δὲ ταῖς συννεφέσι νυξὶ τῇ σελήνῃ προσεκτέον, ἐπεὶ διὰ τὸ μέγεθος ὡς ἐπίπαν αἰεὶ τὸ ταύτης ἐμφαίνεται φῶς, καθʼ ὃν ἂν ᾖ τόπον τοῦ κόσμου.
But on cloudy nights, one must attend to the moon, since because of its size its light is almost always visible, in whatever place of the celestial sphere it may be.
§9.15.13καὶ ποτὲ μὲν ἐκ τῶν περὶ τὰς ἀνατολὰς καιρῶν καὶ τόπων στοχαστέον, §9.15.14ποτὲ δὲ πάλιν ἐκ τῶν περὶ τὰς δύσεις, καθυπαρχούσης καὶ περὶ τοῦτο τὸ μέρος ἐννοίας ἐπὶ τοσοῦτον ὥστε συμπεριφέρεσθαι ταῖς καθʼ ἡμέραν διαφοραῖς τῶν ἀνατολῶν.
And sometimes one must calculate from the times and places of its rising, sometimes again from those of its setting, provided that there is already an understanding of this matter sufficient to follow the daily variations of its rising.
§9.15.15ἔστι δὲ τρόπος εὐθεώρητος καὶ περὶ ταύτην· ὅρος γὰρ εἷς μὴν ὡς τύπῳ, καὶ πρὸς αἴσθησιν
And there is an easily observed method concerning this too; for one month is, roughly speaking, a single limit, and to our perception—