This is Caleb's tattoo.
I've always felt that the success of our own plans are so subject to things outside our control. This quote reflects that.
Submitted by Kurt:
Lee's hand shook as he filled the delicate cups. He drank his down in one gulp. "Don't you see?" he cried. "The American Standard translation orders men to triumph over sin, and you can call sin ignorance. The King James translation makes a promise in 'Thou shalt,' meaning that men will surely triumph over sin. But the Hebrew word, the word timshel—'Thou mayest'— that gives a choice. It might be the most important word in the world. That says the way is open. That throws it right back on a man. For if 'Thou mayest'—it is also true that 'Thou mayest not.' Don't you see?"
- Excerpt from East of Eden by John Steinbeck