The originator of that quote was writing in the 12th century. The quote is cited without a source at https://en.wikipedia.org/wiki/Square_of_opposition https://

The originator of that quote was writing in the 12th century. The quote is cited without a source at https://en.wikipedia.org/wiki/Square_of_opposition https://en.wikipedia.org/wiki/Square_of_opposition , where the phrase is "Omnis homo qui lapis est" ("every man who is a stone"). I haven't dug any further than that. But the phrase literally is intended to indicate a contradiction.