In his second letter to Welser, Galileo describes his method of drawing sunspot diagrams, such as the one at left, through projection: “Expose a flat white sheet of paper about a foot from the concave lens; upon this will fall a circular image of the sun’s disk, with all the spots that are on it arranged and disposed with exactly the same symmetry as in the sun. . . . Thus they will be seen without damage to the eye, even the smallest of them.”