Insight into evangelism?

"I'd look at one of my stonecutters hammering away at the rock, perhaps a hundred times without as much as a crack showing in it. Yet, at the hundred and first blow it would split in two, and I knew it was not the blow that did it, but all that had gone before."

- Jacob August Riis

And no, I'm not talking about evangelism as a series of crippling blows...look at the Riis comment as a metaphor of long-term action and caring, not a direct parallel. :)