One of my favorites: Dr. Edmund Clowney, lecturing on typology and hermeneutics, addressed the position that we can only find types in the OT that are mentioned in the NT. He said:
That’s like saying that we’re only allowed to do a problem in a math textbook if the answer to that problem is given in the answer key in the back of the book.
What a great memory! I recall he added some interesting tidbits from Langer’s Philosophy in a New Key.
I still have his talks on tape. I think his sermon on Exodus 17 was masterful – showing how Clowney truly was one of the best preachers of his generation.