- History does not always repeat itself. Sometimes it just yells, 'Can't you remember anything I told you?' and lets fly with a club.
- Statement in Analog Science Fiction/Fact magazine (1965)
- Immunity corrupts; absolute immunity corrupts absolutely.
- Editorial in Analog Science Fiction/Fact magazine (1970)
- Of course, I never wrote the "important" story, the sequel about the first amplified human. Once I tried something similar. John Campbell's letter of rejection began: "Sorry — you can't write this story. Neither can anyone else."