Doctrinal Books vs. Devotional Books

"For my own part I tend to find the doctrinal books more helpful in devotion than the devotional books, and I rather suspect that the same experience may await many others. I believe that many who find that 'nothing happens' when they sit down, or kneel down, to a book of devotion, would find that the heart sings unbidden while they are working their way through a tough bit of theology with a pipe in their teeth and a pencil in their hand." - C.S. Lewis