Ἰνδικά 43: Arrian. Exp. Alex. VII, 2, 4: Dandamis gymnosophista Alexandrum convenire repudiavit

43

Οὐκοῦν οὐδὲ Ἀλέξανδρον ἐπιχειρῆσαι βιάσασθαι, γνόντα ἐλεύθερον ὄντα τὸν ἄνδρα· ἀλλὰ Κάλανον γὰρ ἀναπεισθῆναι τῶν ταύτῃ σοφιστῶν, ὅντινα μάλιστα δὴ αὑτοῦ ἀκράτορα Μεγασθένης ἀνέγραψεν· αὐτούς τε τοὺς σοφιστὰς λέγειν κακίζοντας τὸν Κάλανον, ὅτι ἀπολιπὼν τὴν παρὰ σφίσιν εὐδαιμονίαν, ὁ δὲ δεσπότην ἄλλον ἢ τὸν θεὸν ἐθεράπευε.

Clem. Alex. Strom. I. p. 305, A, B (ed. Colon. 1688).
Of the Philosophers of India.
[Philosophy, then, with all its blessed advantages to man, flourished long ages ago among the barbarians, diffusing its light among the Gentiles, and eventually penetrated into Greece. Its hierophants were the prophets among the Egyptians, the Chaldæans among the Assyrians, the Druids among the Gauls, the Sarmanæans who were the philosophers of the Baktrians and the Kelts, the Magi among the Persians, who, as you know, announced beforehand the birth of the Saviour, being led by a star till they arrived in the land of Judæa, and among the Indians the Gymnosophists, and other philosophers of barbarous nations.]
There are two sects of these Indian philosophers—one called the Sarmanai and the other the Brachmanai. Connected with the Sarmanai are the philosophers called the Hylobioi, who neither live in cities nor even in houses. They clothe themselves with the bark of trees, and subsist upon acorns, and drink water by lifting it to their mouth with their hands. They neither marry nor beget children [like those ascetics of our own day called the Enkratêtai. Among the Indians are those philosophers also who follow the precepts of Boutta, whom they honour as a god on account of his extraordinary sanctity.]