"What I have learned from about twenty-years of serious reading is this. . What changes my life is some new glimpse of truth, some powerful challenge, some resolution to a long-standing dilemma, and these usually come concentrated in a sentence or two. I do not remember 99% of what I read, but if the 1% of each book or article I do remember is a life-changing insight, then I don't begrudge the 99%. And that life-changing insight usually comes in a moment, a moment whose value is all out of proportion to its little size. That's why I call it an "immeasurable moment."
~John Piper, full transcript available here