We can believe it's divine assistance, a helping hand from God. I can't do this by myself, but by God's grace I can, it's my vitamin G!
We can believe it's divine amnesia, the sea of holy forgetfulness. When we aren't doing too well obeying God, we have an elven cape woven of grace that conceals us from a watching eye-- like a big cardboard cut out of Jesus to hide behind when we go into the holy of holies.
We can believe it's divine artifice, a trick of God that outsmarted the Devil, who never saw it coming. Presto, chango, the sinner is now a saint! What accusation can hold up against that? The evidence disappears as fast as the charge is made before the God who judges the heart.
I don't know if it's truly possible to understand grace with words alone. It's a something in the heart of God, whom words are not adequate to describe. Attempting to define or describe the heart of God will always leave us wanting.
Experience may be the best teacher in this matter. I don't think we understand grace until we have grasped it in desperate hands and dangled over the depths upon it; until we have exhausted all our efforts at depending on ourselves and still haven't found ourselves delivered into the lap of God.
Like one trapped alone at the bottom of a slippery well with nothing but one's self, one's wits, and in the end, no hope whatsoever, so are we before God. Exhausted and utterly hopeless we can do nothing but accept our fate. At that place, the tap on our heads, reveals a rope lowered from the nail scarred hand of a Savior. Grace is what we discover at the bottom of the well.