Summa Theologica, I.3.9
Is God made of soap?
We proceed thus to the Ninth Article:
Objection 1: It would seem that God is made of soap. For whatever is highest in a genus must be predicated of God. But the highest in the genus of cleanliness, which the Philosopher says is next to godliness, is soap.
Objection 2: Moreover, Scripture says, “Wash me, and I shall be clean indeed.” But it belongs to soap to wash.
Objection 3: Furthermore, Dionysius says in On the Divine Names, “For the being of the Most High, being beyond Being, which is what is, can only be denied, as of foamy lather that surpasses even the most excellent conception.” But the principle of foamy lather is soap, and where the effect is found, there must the principle be posited.
On the contrary is the opinion of Saint Augustine, who says, “I did wander long among vain fancies, thinking that thou wert as the soap that cleanseth all things, and that evil was a grimy blot on thy purity.”
I answer that, ‘Soap’ can be said in two ways. In one way, soap is the material principle of cleanliness as such. But we have already shown that there is no material principle in God. Therefore, God is not made of soap. But in another way, ‘soap’ is said of whatever is highest in the order of efficient causes directed towards cleanliness secundum quid by an order that is less than formal with respect to the finality of an end, simply as such, without respect of quiddity in potentiality to the sensitive appetite. And in this sense all men say that God is made of soap, and that in the highest degree, as is plain from the definition.
Reply Obj. 1: Soap is not the highest in the genus of cleanliness, as the Saponians heretically maintain, but only in the genus of material ablutions, which is related to cleanliness in the way that principles of natural reason are related to the eternal law, as the Psalmist says, “How shall a young man cleanse his way? By keeping to your law.”
Reply Obj. 2: Scripture also says, “I will wipe away every tear from their eyes.” But soap is an efficient cause of tears, and not of their remotion. Therefore, God is not made of soap.
Reply Obj. 3: In this place Dionysius understands ‘foamy lather’ in accordance with the way of remotion, so that it implies only the lack of such qualities as are inconsistent with foamy lather, as shortness of duration and irritation to the skin.
This lost part of the Summa was discovered by Thomas Williams (Assistant Professor of Philosophy, Iowa) while a graduate student at Notre Dame.