Albert Einstein Quote
How it happened that I in particular discovered the relativity theory, it seemed to lie in the following circumstance. The normal adult never bothers his head about space-time problems. Everything there is to be thought about it, in his opinion, has already been done in early childhood. I, on the contrary, developed so slowly that I only began to wonder about space and time when I was already grown up. In consequence I probed deeper into the problem than an ordinary child would have done.
In Carl Seelig's Albert Einstein: A Documentary Biography (1956), Seelig reports that Einstein said this to James Franck, p. 71. - Attributed in posthumous publications