Γεωγραφικα 15.1.25

15.1.25

καὶ τοῦτο δὲ τῶν ὁμολογουμένων ἐστὶ καὶ τῶν σωζόντων τὴν πρὸς τὴν Αἴγυπτον ὁμοιότητα καὶ τὴν Αἰθιοπίαν, ὅτι τῶν πεδίων ὅσα μὴ ἐπίκλυστα, ἄκαρπά ἐστι διὰ τὴν ἀνυδρίαν. Νέαρχος δὲ τὸ ζητούμενον πρότερον ἐπὶ τοῦ Νείλου πόθεν ἡ πλήρωσις αὐτοῦ, διδάσκειν ἔφη τοὺς Ἰνδικοὺς ποταμοὺς ὅτι ἐκ τῶν θερινῶν ὄμβρων συμβαίνει· Ἀλέξανδρον δʼ ἐν μὲν τῷ Ὑδάσπῃ κροκοδείλους ἰδόντα, ἐν δὲ τῷ Ἀκεσίνῃ κυάμους Αἰγυπτίους, εὑρηκέναι δόξαι τὰς τοῦ Νείλου πηγάς, καὶ παρασκευάζεσθαι στόλον εἰς τὴν Αἴγυπτον ὡς τῷ ποταμῷ τούτῳ μέχρι ἐκεῖσε πλευσόμενον· μικρὸν δʼ ὕστερον γνῶναι διότι οὐ δύναται ὃ ἤλπισε· μέσσῳ γὰρ μεγάλοι ποταμοὶ καὶ δεινὰ ῥέεθρα, Ὠκεανὸς μὲν πρῶτον, εἰς ὃν ἐκδιδόασιν οἱ Ἰνδικοὶ πάντες ποταμοί, ἔπειτα ἡ Ἀριανὴ καὶ ὁ Περσικὸς κόλπος καὶ ὁ Ἀράβιος καὶ αὐτὴ ἡ Ἀραβία καὶ ἡ Τρωγλοδυτική. τὰ μὲν οὖν περὶ τῶν ἀνέμων καὶ τῶν ὄμβρων τοιαῦτα λέγεται καὶ τῆς πληρώσεως τῶν ποταμῶν καὶ τῆς ἐπικλύσεως τῶν πεδίων.

It is admitted by those who maintain the resemblance of India to Egypt and Ethiopia, that the plains which are not overflowed do not produce anything for want of water.
Nearchus says, that the old question respecting the rise of the Nile is answered by the case of the Indian rivers, namely, that it is the effect of summer rains; when Alexander saw crocodiles in the Hydaspes, and Egyptian beans in the Acesines, he thought that he had discovered the sources of the Nile, and was about to equip a fleet with the intention of sailing by this river to Egypt; but he found out shortly afterwards that his design could not be accomplished, for in midway were vast rivers, fearful waters, and first the ocean, into which all the Indian rivers discharge themselves; then Ariana, the Persian and Arabian Gulfs, all Arabia and Troglodytica.
The above is what has been said on the subject of winds and rains, the rising of rivers, and the inundation of plains.