ANSWER: The best three are: (1) the Bible, (2) Nature and (3) experience. A thorough study of those will furnish you with abundant illustrations pertinent and instructive. Cultivate the habit of seeing spiritual truths in the natural world and in the events of daily life. As for cyclopedias of illustration, the less you use them the better for your sermons and your self-respect. In my youthful ministry I cumbered my library with them, but I got rid of them so long ago that I have forgotten the names of their compilers. Become your own cyclopedia. Jesus often said, "The kingdom of heaven is like." Keep on the lookout for likes. If you wish to know what attractiveness they give to a sermon when the preacher is the discoverer of the likeness, read a volume of Rev. Louis Albert Banks, as a modern instance.
— Steele's Answers pp. 102, 103.