Since today is the feast day of St Gregory…
“…for there are certain things derived from profane educataion which should not be rejected when we propose to give birth to virtue. Indeed, moral and natural philosophy may become at certain times a comrade, friend, and companion of life to the higher way, provided that the offspring of this union introduce nothing of a foreign defilement.
Since [Moses’ son] had not been circumcised, so as to cut off completely everything hurtful and impure, the angel who met [Moses and Zipporah returning into Egypt] brought the fear of death. His wife appeased the angel when she presented her offspring as pure by completely removing that mark by which the foreigner was known.
I think that if someone who has been initiated under the guidance of the history follows closely the order of the historical figures, the sequence of development in virtue marked out in our account will be clear. There is something fleshly and uncircumcised in what is taught by philosophy’s generative faculty; when that has been completely removed, there remains the pure Israelite race.
For example, pagan philosophy says that the soul is immortal. This is a pious offering. But it also says that souls pass from bodies to bodies and are changed from a rational to an irrational nature. This is a fleshly and alien foreskin. And there are many other such examples. It says there is a God, but it thinks of him as material. It acknowledges him as Creator, but says he needed matter for creation. It affirms that he is both good and powerful, but that in all things he submits to the necessity of fate.
And one could describe in some detail how good doctrines are contaminated by profane philosophy’s absurd additions. When these are completely removed, the angel of God comes to us in mercy, as if rejoicing in the true offspring of these doctrines.”
-St Gregory of Nyssa, from The Life of Moses