I have to state that my studies in Philo lead me to regard him as an apologist, and a preacher, and to have no great confidence in the reliability of his reports on either the Therapeutae or the Essenes. In the case of the latter, I suspect we deal with Philo’s third-hand knowledge and not his direct contact on any intensive basis, for Philo was an Alexandrian whose known visits to Palestine turn out to number exactly one. … Hence, I find myself somewhat disinclined to take Philo’s historical statements too seriously. … Indeed, when I consider the apologetic tendencies, and concomitant distortions, in both Philo and Josephus, I find myself taking what they say with elaborate grains of salt. Josephus tells us that the Essenes were Neo-Pythagoreans. Indeed, he makes philosophers out of all Jews, equating the movements with Greek philosophical schools. To my mind, we encounter in Josephus not precision but pretension.
I do not trust what Philo and Josephus tell about the Essenes.
Samuel Sandmel, “Parallelomania”, Journal of Biblical Literature vol 81, No. 1 (March 1962), 7-8.