The Blessed Cannot Sin

The blessed cannot sin because they possess happiness itself. But I think that's a special case and it doesn't apply to us in this life. We're never faced, we're never in possession of a perfect and perfectly fulfilling, unmitigated good in thislife. And when faced with multiple incommensurate goods, which is what we're always faced with in choices in this life, to some degree the will decides what our preferences are.