Richard Foster wrote Celebration of Discipline "for all those disillusioned by the superficialities of modern culture, including modern religious culture." He struck a nerve. Since its publication in 1978, Celebration has sold more than 1.5 million copies in 14 languages. Through his writing and his ministry, Renovaré, Foster has reintroduced evangelicals to spiritual formation. Brandon O'Brien talked to Foster about it all.

Why did Celebration of Discipline do so well?

It appeared at a point in history when people sensed the way we were doing ministry wasn't working. Leaders were lost to moral failures. People wanted something more substantial. There was a longing to connect to the great historical conversation about the growth of the soul. Most people were only aware of the early church and then us today—maybe a few had heard of the Reformation. With Celebration I introduced people to the historical conversation.