“What is the question now placed before society with the glib assurance the most astounding? That question is this—Is man an ape or an angel? My lord, I am on the side of the angels.”

Source: The Long Hard Road Out of Hell

Source: The Naked Ape: A Zoologist's Study of the Human Animal

Source: The Life of St. Teresa of Jesus (c.1565), Ch. XXIX, ¶ 16-17
Context: I saw an angel close by me, on my left side, in bodily form. This I am not accustomed to see, unless very rarely. Though I have visions of angels frequently, yet I see them only by an intellectual vision, such as I have spoken of before. It was our Lord's will that in this vision I should see the angel in this wise. He was not large, but small of stature, and most beautiful — his face burning, as if he were one of the highest angels, who seem to be all of fire: they must be those whom we call cherubim. Their names they never tell me; but I see very well that there is in heaven so great a difference between one angel and another, and between these and the others, that I cannot explain it.I saw in his hand a long spear of gold, and at the iron's point there seemed to be a little fire. He appeared to me to be thrusting it at times into my heart, and to pierce my very entrails; when he drew it out, he seemed to draw them out also, and to leave me all on fire with a great love of God. The pain was so great, that it made me moan; and yet so surpassing was the sweetness of this excessive pain, that I could not wish to be rid of it. The soul is satisfied now with nothing less than God. The pain is not bodily, but spiritual; though the body has its share in it, even a large one. It is a caressing of love so sweet which now takes place between the soul and God, that I pray God of His goodness to make him experience it who may think that I am lying.</p

Source: Hogfather

"The Retreat," l. 1.
Silex Scintillans (1655)

A similar remark was reportedly made by Pratchett in The Herald (4 October 2004): I'd rather be a climbing ape than a falling angel.
"I create gods all the time - now I think one might exist" (2008)
Context: Evolution was far more thrilling to me than the biblical account. Who would not rather be a rising ape than a falling angel? To my juvenile eyes Darwin was proved true every day. It doesn't take much to make us flip back into monkeys again.

Source: The Martyrdom of Man (1872), Chapter III, "Liberty"

The Tragic Sense of Life (1913), VII : Love, Suffering, Pity