Strabo thought that besides the world known to the Greeks and Romans, other continents or worlds, where other races of men dwelt, might be discovered.
In a work called "Suasoriæ" (circa 37 A.D.) of the Spanish-born rhetorician Seneca there are preserved fragments of a poem, written by Albinovanus Pedo (in the time of Augustus), which described an expedition of Germanicus in the North Sea. It has been thought that this may have been the younger Germanicus's unfortunate campaign in 16 A.D., when he sailed out from the Ems with a fleet of a thousand ships. This supposition is strengthened by the fact that Tacitus mentions a cavalry leader, Albinovanus Pedo, under the same commander in 15 A.D., and it is easy to believe that he was the poet.[78] But as this unhappy fleet did not get far from the coast, and the poem describes a voyage into unknown regions, others have thought that it might be an expedition undertaken by Drusus, the elder Germanicus, in some year between 12 and 9 B.C.[79] How this may be is of less importance to us, as the poem does not mention any fresh discoveries. It is interesting because it gives us a picture of the ideas current at that time about the northern limits of the world. Where the fragments commence, the travellers have long ago left daylight and the sun behind them, and, having passed beyond the limits of the known world, plunge boldly into the forbidden darkness towards the end of the western world. There they believe that the sea, which beneath its sluggish ("pigris") waves is full of hideous monsters, savage whales ("pistris"), and sea-hounds ("æquoreosque canes" == seals ?), rises and takes hold of the ship--the noise itself increases the horror--and now they think the ships will stick in the mud, and the fleet will remain there, deserted by the winds[80] of the ocean--now that they themselves will be left there helpless and be torn to pieces by the monsters of the deep. And the man who stands high in the prow strives with his eyes to break through the impenetrable air, but can see nothing, and relieves his oppression in the following words: "Whither are we being carried? The day itself flees from us, and uttermost nature closes in the deserted world with continual darkness. Or are we sailing towards people on the other side, who dwell under another heaven, and towards another unknown world?[81] The gods call us back and forbid the eyes of mortals to see the boundary of things. Why do we violate strange seas and sacred waters with our oars, disturbing the peaceful habitations of the gods?"