THE TOWER HAD FEW WINDOWS, and the few that it did have were small, and shuttered tight, but after several circumnavigations of the structure Leibniz found a slat that was slightly askew and permitted him, if he stood on his toes, to peer inside. Outside it was bright and clear but inside the observatory it was dark apart from the light of a single candle, which dimly illuminated a very old man sitting on a three-legged stool, pressing one of his two empty eye sockets to the brass eyepiece of that colossal telescope. He neither wore glass eyes nor covered his sockets with patches; where the eyes are usually found “he merely had two uncanny voids.” Obviously someone at some point had simply gone ahead and plucked them out. Every so often the astronomer would suddenly pick up his quill and write something down with considerable urgency, and although Leibniz could not make out from his vantage point what it was the astronomer was writing, “he gave off at such moments the distinct impression of someone who has really seen something.” If this was a sort of performance, it was not clear for whom he might be performing, since there was no one else save a fat slumbering cat in the observatory, and as far as Leibniz could tell, he, Leibniz, had not yet been detected. If this was a performance for God, God, the being that need only be possible to be actual, and Who therefore is actual, because He is possible, and Who as a consequence of His actuality perceives at every instant an infinity of perceptions, would, no doubt, not be fooled, a fact of which reason itself, if it functioned rightly in him, would inform the astronomer. And if it is a performance for himself, he is, as I will prove, mad, Leibniz wrote, for it is part of the essence of a performance that one stages it for others, so anyone who performs for himself acts as if he has within him another being, who might be performed for—an evident absurdity; and if he believes this absurdity, then he is mad, and if he acts this way without believing it, then he is also mad. Hence, Leibniz reasoned, if this “ceremony of sight” (my translation) is performed for himself, then he is mad; if it is performed for God, then he is also mad; and if it is performed for others, there being no one else here besides me, whom as far as I can tell he has not detected, then he is also mad. So, if he is sane, and he has not detected me, then this is not a performance, and either he really sees, or he thinks he really sees.