"Thales,
so the story goes, because of his poverty was taunted with the uselessness of
philosophy; but from his knowledge of astronomy he had observed while it was still
winter that there was going to be a large crop of olives, so he raised a small
sum of money and paid round deposits for the whole of the olive-presses in Miletus and Chios, which he hired at a low rent as nobody
was running him up; and when the season arrived, there was a sudden demand for
a number of presses at the same time, and by letting them out on what terms he
liked he realized a large sum of money, so proving that it is easy for
philosophers to be rich if they choose, but this is not what they care
about."
Aristotle, Politics, Book 1, section 1259a