" The German astronomer Johannes Kepler coined the term “camera obscura” in the early seventeenth century, but by then the phenomenon had been known for millennia; in fact, it is perhaps the oldest known optical illusion. Some form of camera obscura was most likely behind a popular illusion performed in ancient Greece and Rome, in which spectral images were cast upon the smoke of burning incense by performers using concave metal mirrors—hence the expression “smoke and mirrors. "

― Jennifer Ouellette