hay que demostrar
From LSJ
ἄνω ποταμῶν ἱερῶν χωροῦσι παγαί → the springs of sacred rivers flow upward, backward to their sources flow the streams of holy rivers
ἄνω ποταμῶν ἱερῶν χωροῦσι παγαί → the springs of sacred rivers flow upward, backward to their sources flow the streams of holy rivers
βεβαιωτέον, ἀποδεικτέον, δεικτέον