27 But both Greeks and Jews harass us and say that it was impossible for the Christ to be born of a virgin. As for the Greeks we will stop their mouths from their own fables. For you who say that stones being thrown were changed into men, how do you say that it is impossible for a virgin to bring forth? You who fable that a daughter was born from the brain, how do you say that it is impossible for a son to have been born from a virgin's womb? You who falsely say that Dionysus was born from the thigh of your Zeus, how set ye at nought our truth? I know that I am speaking of things unworthy of the present audience: but in order that you in due season may rebuke the Greeks, we have brought these things forward answering them from their own fables.
Source: Catechetical Lectures (New Advent)