"Time must be found for reading, and we turn now to the more intellectual type of reading. The first is theology. There is no greater mistake than to think that you finish with theology when you leave a seminary. The preacher should continue to read theology as long as he is alive. The more he reads the better and there are many authors and systems to be studied. I have known men in the ministry, and men in various other walks of life who stop reading when they finish their training. They think they have acquired all they need; they have their lecture notes, and nothing further is necessary. The result is that they vegetate and become quite useless. Keep on reading; and read the big works."
From Preaching and Preachers by D.Martyn Lloyd-Jones, Hodder and Stoughton, 1985, p. 177.