 He suggested to use it to view "what takes place in the street when the sun shines" and advised to use a very white sheet of paper as a projection screen so the colours wouldn't be dull.Sicilian mathematician and astronomer Francesco Maurolico (1494–1575) answered Aristotle's problem how sunlight that shines through rectangular holes can form round spots of light or crescent-shaped spots during an eclipse in his treatise "Photismi de lumine et umbra" (1521–1554).However this wasn't published before 1611, after Johannes Kepler had published similar findings of his own.