38 As an example of those particulars which have no meaning at all if not a symbolic one: Granting that it was necessary that woman should be made as an help meet for man, what natural reason can be assigned for her being taken from his side while he slept? Granting that an ark was required in order to escape from the flood, why should it have precisely these dimensions, and why should they be recorded for the devout study of future generations? Granting that the animals were brought into the ark to preserve the various races, why should there be seven clean and two unclean?
Granting that the ark must have a door, why should it be in the side, and why should this fact be committed to writing? Abraham is commanded to sacrifice his son: we may allow that this proof of his obedience was required in order to make it conspicuous in all ages; we may allow, too, that it was a proper thing for the son to carry the wood instead of the aged father, and that in the end the fatal stroke was forbidden, lest the father should be left childless. But what had the shedding of the ram's blood to do with Abraham's trial?
Or if it was necessary to complete the sacrifice, was the ram any the better of being caught by the horns in a bush? The human mind, that is to say, a rational mind, is led by the consideration of the way in which these apparently superfluous things are blended with what is necessary, first to acknowledge their significance, and then to try to discover it.
Source: Reply to Faustus the Manichaean (New Advent)