Quintus Curtius Rufus, History of Alexander 9.9.2

9.9.2

navigabant ergo omnium, per quae ferebantur, ignari. Quantum inde abesset mare, quae gentes colerent, quam placidum amnis os, quam patiens longarum navium esset, anceps et caeca aestimatio augurabatur: unum erat temeritatis solacium perpetua felicitas.

Here he was obliged to make a longer stay than he had anticipated, because the pilots, finding they were not strictly guarded, had absconded. He then sent out a party of his men to search for others. They returned without finding any, but his unquenchable ambition to see the ocean and reach the boundaries of the world, made him entrust his own life and the safety of so many gallant men to an unknown river without any guides possessed of the requisite local knowledge. They thus sailed on ignorant of everything on the way they had to pass. It was entirely left to haphazard and baseless conjecture how far off they were from the sea, what tribes dwelt along the banks, whether the river was placid at its mouth, and whether it was thereabouts of a depth sufficient for their war-ships. The only comfort in this rash adventure was a confident reliance on Alexander's uniform good fortune. The expedition had in this manner now proceeded a distance of 400 stadia, when the pilots brought to his notice that they began to feel sea-air, and that they believed the ocean was not now far off.