Philo Judaeus De Opificio Mundi 114

Moreover, the constellation Ursa Major, which men call the guide of mariners, consists of seven stars, which the pilots keeping in view, steer in innumerable paths across the sea, directing their endeavours towards an incredible task, beyond the capacity of human intellect. For it is through conjectures, directed by the aforementioned stars, that they have discovered countries which were previously unknown; those who dwell on the continent having discovered islands, and islanders having found out continents. For it was fitting that the recesses both of earth and sea should be revealed to that God-loving animal, the race of mankind, by the purest of essences, namely heaven.