I've suspected for a long time that that was the insight Carl Sagan had while high and showering with his wife:

I can remember one occasion, taking a shower with my wife while high, in which I had an idea on the origins and invalidities of racism in terms of gaussian distribution curves. It was a point obvious in a way, but rarely talked about. I drew the curves in soap on the shower wall, and went to write the idea down. One idea led to another, and at the end of about an hour of extremely hard work I found I had written eleven short essays on a wide range of social, political, philosophical, and human biological topics. Because of problems of space, I can’t go into the details of these essays, but from all external signs, such as public reactions and expert commentary, they seem to contain valid insights.

(It is a little interesting, & amusing, to see someone inferring the "invalidit[y] of racism" from an observation more often used as a justification for racial hereditarian attitudes!)