§3.51.1παραδόξου δʼ εἶναι δοκοῦντος τοῦ πράγματος καὶ μύθῳ πεπλασμένῳ παραπλησίου, πειρῶνταί τινες τῶν φυσικῶν αἰτίας ἀποδιδόναι τοῦ γινομένου τοιαύτας.
Since this matter seems to be paradoxical and resembling a fabricated myth, some of the natural philosophers attempt to assign such causes as follow for what happens.
§3.51.2ἀνέμους φασὶ κατὰ τὴν χώραν τοὺς μὲν τὸ σύνολον μὴ πνεῖν, τοὺς δὲ παντελῶς εἶναι βληχροὺς καὶ κωφούς· ὑπάρχειν δὲ καὶ περὶ τὸν ἀέρα πολλάκις ἠρεμίαν καὶ θαυμαστὴν ἀκινησίαν διὰ τὸ μήτε νάπας μήτε συσκίους αὐλῶνας παρακεῖσθαι πλησίον μήτε λόφων ὑπάρχειν ἀναστήματα· ποταμῶν τε μεγάλων σπανίζειν τοὺς τόπους, καὶ καθόλου τὴν σύνεγγυς χώραν ἅπασαν ἄκαρπον οὖσαν μηδεμίαν ἔχειν ἀναθυμίασιν· ἐξ ὧν ἁπάντων εἰωθέναι γεννᾶσθαί τινας ἀρχὰς καὶ συστάσεις πνευμάτων.
For they say that, as for the winds throughout this country, some do not blow at all, while others are entirely weak and faint; and that there often exists about the air a stillness and wonderful immobility, because neither glens nor shaded valleys lie near, nor do there exist any elevations of hills; and that the regions lack large rivers, and in general the entire adjacent land, being barren, has no exhalation; from all of which things it is customary for certain sources and combinations of winds to be generated.
§3.51.3διόπερ συμπνιγοῦς περιστάσεως τὴν χέρσον ἐπεχούσης, ὅπερ ὁρῶμεν ἐπὶ τῶν νεφῶν ἐνίοτε συμβαῖνον ἐν ταῖς νοτίαις ἡμέραις, τυπουμένων ἰδεῶν παντοδαπῶν, τοῦτο γίνεσθαι καὶ περὶ τὴν Λιβύην, πολλαχῶς μορφουμένου τοῦ συμπίπτοντος ἀέρος·
Therefore, when a stifling condition holds the dry land—just as we see sometimes happening in the case of clouds on days with south winds, when all kinds of shapes are formed—this also happens regarding Libya, since the condensing air is formed in many ways.
ὃν ταῖς μὲν ἀσθενέσι καὶ βληχραῖς αὔραις ὀχεῖσθαι μετεωριζόμενον καὶ παλμοὺς ποιοῦντα καὶ συγκρούοντα συστήμασιν ἑτέροις ὁμοίοις, νηνεμίας δʼ ἐπιλαμβανούσης καθίστασθαι πρὸς τὴν γῆν, βαρὺν ὄντα καὶ τετυπωμένον ὡς ἔτυχεν· ἔπειτα μηδενὸς ὄντος τοῦ συγχέοντος προσπελάζειν τοῖς αὐτομάτως περιτυγχάνουσι τῶν ζῴων.
This air is carried aloft by weak and faint breezes, causing vibrations and colliding with other similar aggregates, but when a calm takes over, it settles toward the earth, being heavy and shaped by chance; then, since there is nothing to disperse it, it approaches those animals which happen to meet it.
§3.51.4τὰς δʼ ἐφʼ ἑκάτερα κινήσεις αὐτῶν φασι προαίρεσιν μὲν μηδεμίαν ἐμφαίνειν· ἐν ἀψύχῳ γὰρ ἀδύνατον ὑπάρχειν φυγὴν ἑκούσιον ἢ δίωξιν· τὰ μέντοι ζῷα λεληθότως αἴτια τῆς μεταρσίας κινήσεως γίνεσθαι·
And they say that their movements in either direction show no intention; for in an inanimate thing it is impossible for voluntary flight or pursuit to exist; however, the animals, without being noticed, become the causes of their movement in the air.
προσιόντων μὲν γὰρ αὐτῶν τὸν ὑποκείμενον ἀέρα μετὰ βίας ἀναστέλλειν, καὶ διὰ τοῦθʼ ὑποχωρεῖν τὸ συνεστηκὸς εἴδωλον καὶ ποιεῖν τὴν ἔμφασιν ὑποφεύγοντος· τοῖς δʼ ἀναχωροῦσι κατὰ τοὐναντίον ἐπακολουθεῖν, ἀντεστραμμένης τῆς αἰτίας, ὡς ἂν τοῦ κενοῦ καὶ τῆς ἀραιώσεως ἐπισπωμένης.
For as they approach, they violently push back the underlying air, and because of this, the consolidated image retreats and presents the appearance of fleeing; but conversely, it follows those who withdraw, because the cause is reversed, as if the vacuum and rarefaction were drawing it.
§3.51.5διόπερ ἐοικέναι διώκοντι τοὺς ὑποχωροῦντας· ἕλκεσθαι γὰρ αὐτὸ καὶ προπίπτεὶν εἰς τὸ πρόσθεν ἄθρουν ὑπὸ τῆς πάλιν ῥύμης· τοὺς δʼ ὑποφεύγοντας, ὅταν ἐπιστραφῶσιν ἢ μένωσιν, εὐλόγως ὑπὸ τοῦ συνακολουθοῦντος εἰδώλου ψαύεσθαι τοῖς ὄγκοις· τοῦτο δὲ κατὰ τὴν πρὸς τὸ στερέμνιον πρόσπτωσιν περιθρύβεσθαι, καὶ πανταχόθεν προσχεόμενον καταψύχειν τὰ σώματα τῶν περιτυγχανόντων.
Therefore, it resembles one pursuing those who withdraw; for it is drawn and thrust forward all at once into the space ahead by the backward rush of air; but as for those who flee, when they turn around or stand still, they are naturally touched in their bulk by the accompanying image; and this, upon its impact against the solid body, is shattered, and pouring around from all sides, cools the bodies of those who encounter it.