Why is it that [Mozart] is so incomparable? ... He has heard, and causes those with ears to hear, even today, what we shall not see until the end of time-the whole context of providence. As though in the light of this end, he heard the harmony of creation to which the shadow belongs but in which the shadow is not darkness, deficiency is not defeat, sadness cannot become despair, trouble cannot degenerate into tragedy and infinite melancholy is not ultimately forced to claim undisputed sway ... Mozart causes us to hear that even on the latter side, and therefore in its totality, creation praises its master and is therefore perfect.
(Karl Barth, cited in pp.348-349, Colin Gunton, "Mozart the Theologian", Theology, (1991) 94)
Which is a bit like one of the points Jeremy Begbie makes in this interesting little video a friend sent to me:
At about 5min he explains that in playing the piano, as in life:
Once you've made the mistake there is no going back...
You can't delete that mistake.
What you can do is turn it into a passing note.
A passing note is a note that doesn't fit with the underlying harmony that can be made to fit, can be woven into, the context.
I suppose that is one of the most extraordinary things about being a Christian, that God can take your worst mistakes and turn them into his passing notes.