"In Greece burning glasses seem to have been manufactured at an early date. Aristophanes in the comedy of The Clouds... introduces a conversation about "fine transparent stone (glass) with which fires are kindled," and by which, standing in the sun, one can, "though at a distance, melt all the writing" traced on a surface of wax."
January 1, 1970
https://en.wikiquote.org/wiki/A_History_of_Physics_in_its_Elementary_Branches