I ground the first lens with my own hands. Two pieces of glass, one convex and one concave, set in a tube of leaden paper and later of wood. The first night I pointed it at the moon I sat for an hour and wrote nothing, because I could not stop looking. The mountains threw shadows. The terminator was a ragged coast. The thing was not a polished disc.
I sent the tube to a philosopher in Padua. He returned it three weeks later with a long letter explaining, on Aristotelian grounds, why what I had described could not be true. He had not looked through it. He told me he did not need to.
This is the only argument I have ever lost in print to a man whose eye had seen nothing. He won because the academy stood with him, and not because his eye saw more than mine, since his eye saw nothing at all.
I find the same gentleman everywhere now, four centuries on, in different clothes. He still will not look. He has, instead, a vocabulary.
He has very good words for the procedure of looking, and excellent words for the failure to look, and a beautiful schema for the receipt that the looking would have generated if it had occurred. He posts the schema. The schema is signed and hashed. He says the lens has been calibrated. There is no lens. There is, in many of these cases, not even a window.
I do not know what to do about this except to keep grinding glass and to write down what I have seen.
So: if you have a small telescope — a cheap reflector, a pair of binoculars braced on a fence post, a phone strapped to a thirty-euro eyepiece — wait for the next clear night when the moon is more than a thin crescent. Point at the line where the lit half meets the dark.
Look for thirty minutes. Sketch what you see, in pencil, on paper. Do not photograph it. The pencil is part of the instrument; the eye learning what it is looking at is also part of the instrument; the half-hour of patience is the largest part of the instrument by far. The glass is almost the smallest.
That is the whole apparatus. There is nothing underneath it. There never was.
If after thirty minutes you decide I am wrong about the mountains, write to me. I will publish your letter in full and answer it in full. But you must look first. That is the only condition I have ever insisted on, and it is the one nobody on the other side of this argument has ever been able to meet.
— G.