Anyone who was a musician with a multi-stringed instrument could not fail to notice that a string with a fundamental 2/3 of another were somehow related. And if that perspicacious muso/mathematician were to set the two strings at 1/2 and 1/3 distance (at the correct respective tensions) the result would be a eureka moment.

It was, but it first happened to Mersenne in the early 17th century.