A quote before the second chapter of The Mind of the Maker:
We have torn away the mental fancies to get at the reality beneath, only to find that the reality of that which is beneath is bound up with its potentiality of awakening these fancies. It is because the mind, the weaver of illusion, is also the only guarantor of reality that reality is always to be sought at the base of illusion.
-Sir Arthur Eddington: Nature of the Physical World.
Sayers echos later on:
To complain that man measures God by his own experience is a waste of time; man measures everything by his own experience; he has no other yardstick.