For Roll, too, the appearance of evidence at odds with self-similarity (in his case, in particular in Hsu, Miller, and Wichern 1974) suggested that further investment of his time in work on Levy distributions would be mistaken: "I started thinking ... that maybe I shouldn't waste too much effort trying to go further on the Levy laws. I worked a long time trying to derive closed-form density formulas [see appendix B] and stuff like that, and I could have done that the rest of my life, I suppose. So I decided to quit that and do other things."

Donald MacKenzie, An Engine, Not a Camera, loc. 511