The Rabbis drew their information from personal conversations with philosophers and other intelligent people. The Talmuds and the Midrashim frequently mention such intercourse between the Rabbis and men whom they styled “philosophers.”. It is reasonable to assume that there were many learned Jews among the upper classes of Jewish Palestine who communicated some of the Greek doctrines to the Rabbis.
Saul Lieberman, “How Much Greek in Jewish Palestine?” in Biblical and Other Studies, ed. A. Altmann (Cambridge, MA: Harvard University Press, 1962), 131.