What did it?

When nothing seems to help, I go and look at a stone cutter hammering away at his rock, perhaps a hundred times without as much as a crack showing in it. Yet, at the hundred and first blow, it will split in two; and I know it was not that blow that did it, but all that had gone before. 
                                                                                                                        by Jacob Ris
(Perhaps our prayers work the same way)