G. Reale, A History of Ancient Philosophy: The Schools of the Imperial Age, trans. John R. Catan (Albany: State University of New York Press, 1990) 179.
The foundation of the wisdom of which Philo speaks is faith, understood as firm and unshakeable confidence which is opposed to the uncertainty of human reasoning.
According to Reale, Philo (first century C.E.) drew from the Skeptics in that he acknowledged that human reasoning had its limitations. Reale states that Philo differed from Plato, who thought that rational dialectic was the path to true wisdom.
I can somewhat understand Plato's perspective, since Plato was looking for something iron-clad, that is, rooted in reason. I'm not sure why Philo believed that human reasoning had its limitations, though. Was it because there are competing claims about what is reasonable, or that there are many things that we don't take into consideration when we reason, subjective beings that we are?
Is the faith that Philo advocates blind, in the sense of believing in something without proof? How is this more certain than human reasoning? And doesn't one need human reasoning in order to interpret and understand the divine revelation? Is that what Philo does when he seeks to reconcile the Torah with Greek philosophy? If reason is limited, as the Skeptics argued, how would it be reliable in helping us to understand the divine revelation? I vaguely recall from Yehoshua Amir's article on Philo in Mikra that Philo believed in divine illumination. Yet, I recall reading somewhere that Philo also didn't really hold to divine dictation, so he thought that Moses' reason played some role in his reception and communication of the divine revelation.
Reason may be flawed, but we can't exactly escape it, since it's how people understand the world around them, which includes their books (such as the Bible).