At the outset of Cur Deus Homo? Anselm cannot pull himself away from the beauty of the atonement. To say God humbled himself is not unsuitable ( convenire ) and makes no injury to God. It is perfectly appropriate, as evident from the symmetry of fall and redemption:
Death enters through disobedience, life through obedience; sin originated from a woman, the redeemer was born of a woman; man who fell at a tree is by a tree saved. It is indescribably beautiful ( ineffabilem . . . pulchritudinem ) that redemption should be accomplished hoc modo .
Boso is not convinced: Painters paint on solids, not on air or water. When Christians speak as Anselm speaks, unbelievers think they are merely painting on clouds. An aesthetic theory isn’t enough; some ratio must be invoked.
But Anselm won’t let go of the aesthetics just yet (he does eventually). It seems sufficient reason ( satis necessaria ratio ) that God would not leave mankind, his most precious handiwork ( pretiosum opus eius ) to be destroyed. It would not have been fitting if God had left humanity to be annihilated.
Whatever else Anselm says about the atonement, it is important to see that it begins as a rationalization of an utterly patristic aesthetic delight in the symmetry of Christ’s work.