Perhaps you are thinking of The Door Into Summer: "In Robert Heinlen's The Door Into Summer, Dr. Twitchell recounts a tale of a student whom he displaced in ti

Perhaps you are thinking of The Door Into Summer: "In Robert Heinlen's The Door Into Summer, Dr. Twitchell recounts a tale of a student whom he displaced in time by 500 years. While there was no way of knowing whether the student went to the past or the future, Dr. Twitchell hints that he believes it was the past due to the student's name—Leonard Vincent." https://en.wikipedia.org/wiki/Cultural_references_to_Leonardo_da_Vinci https://en.wikipedia.org/wiki/Cultural_references_to_Leonard...