The potentialities of development in human souls are unfathomable. So many who seemed irretrievably hardened have in point of fact been softened, converted, regenerated, in ways that amazed the subjects even more than they surprised the spectators, that we never can be sure in advance of any man that his salvation by the way of love is hopeless.
 William James, The Varieties of Religious Experience (1902). copy citation

Context

“From this point of view we may admit the human charity which we find in all saints, and the great excess of it which we find in some saints, to be a genuinely creative social force, tending to make real a degree of virtue which it alone is ready to assume as possible. The saints are authors, auctores, increasers, of goodness. The potentialities of development in human souls are unfathomable. So many who seemed irretrievably hardened have in point of fact been softened, converted, regenerated, in ways that amazed the subjects even more than they surprised the spectators, that we never can be sure in advance of any man that his salvation by the way of love is hopeless. We have no right to speak of human crocodiles and boa-constrictors as of fixedly incurable beings. We know not the complexities of personality, the smouldering emotional fires, the other facets of the character-polyhedron, the resources of the subliminal region.” source