"God will sometimes call on the Christian to turn back from the inward and to apply himself to things without. Why? Because that person has become addicted to an inward retreat. Many a believer is quite certain that he will never have to bear this cross; but if leaving inward solitude is the thing necessary in order for us to encounter the cross, then that is what God will do. And God really does sometimes separate a Christian from spiritual things which – perhaps unknown to himself – the Christian is addicted to or prideful in. (Yes, it is quite frequent that a Christian becomes prideful about his inner life, and does not know it!)"
Final Steps in Christian Maturity, pages 38