All during this time he continued to make his nightly observations, and to spread the word concerning the usefulness of his glass. Occhialino, visorio, perspicillum—different people called it different things, and he did, too. He sent excellent glasses to the Duke of Bavaria, the Elector of Cologne, and Cardinal del Monte, among other nobles of court and church. He was now in the service of the Medici, of course, but the Medici would want the capabilities of his glass advertised to as many of the powers in Europe as possible. And it was important to establish the legitimacy of what Galileo had reported in his book by having it confirmed in other places by influential figures. He had heard there were people like Cremonini refusing to look through a glass, and others claiming his new discoveries were merely optical illusions, artifacts of the instrument itself. Indeed, he had suffered an unfortunate demonstration in Bologna, when he had tried to show the famous astronomer Giovanni Magini the Medicean Stars, and only been able to see one himself—which may have been because three were behind Jupiter, but it was a hard case to make, especially with the odious Bohemian climber Martin Horky there smirking at every word, obviously delighted that things weren’t going as planned. Afterward he heard that Horky had written to Kepler telling him that the visorio was a fraud, useless for astronomy.
Kepler was experienced enough to ignore backstabbing by such a loathsome toad, but his characteristically long and incoherent letter in support of Galileo’s discoveries, published as a book for the world to read under the title Dissertatio cum Nuncio Sidereo, was in some ways as bad as the Horky nonsense. Confusions from Kepler were nothing new—although up until this point they had always made Galileo laugh. One time for the sake of his artisans he had translated into Tuscan Kepler’s claim that the music of the spheres was a literal sound made by the planets, a six-note chord that moved from major to minor depending on whether Mars was at perihelia or aphelia. This idea made Galileo laugh so hard he could barely read. “The chapter’s title is ‘Which Planet Sings Soprano, Which Alto, Which Tenor, and Which Bass!’ I swear to God! The greatest astronomer of our time! He admits he has no basis for this stuff except his own desire for it, and then concludes that Jupiter and Saturn must sing bass, Mars tenor, Earth and Venus alto, and Mercury soprano.”
The workshop gang then sang, in their usual four-part harmony, one of their rudest love songs, replacing all the usual girls’ names with “Venus.”
That was Kepler: a good source for jokes. Now, reading Kepler’s defense of Galileo’s spyglass discoveries, Galileo felt an uneasiness that sharpened the further he read. Lots of people would read this book, but much of Kepler’s praise was so harebrained it cut both ways:
I may perhaps seem rash in accepting your claims so readily with no support from my own experience. But why should I not believe a most learned mathematician, whose very style attests to the soundness of his judgment? He has no intention of practicing deception in a bid for vulgar publicity, nor does he pretend to have seen what he has not seen. Because he loves the truth, he does not hesitate to oppose even the most familiar opinions, and to bear the jeers of the crowd with equanimity.
What jeers of the crowd? For one thing there hadn’t been that many, and for another, Galileo did not bear them with equanimity. He wanted to kill every critic he had. He liked fights in the same way bulls are attracted to red—not because it looks like blood, or so they say, but because it has the color of the pulsing parts of cows in heat. Galileo loved to fight like that. And so far he had never lost one. So equanimity had nothing to do with it.
Then further on in Kepler’s sloppy endorsement, he asked what Galileo saw through his perspicillum when he looked at “the left corner of the face of the Man in the Moon,” because it turned out that Kep ler had a theory about that region, which he now propounded to the world—that a mark there was the work of intelligent beings who lived on the moon, who must therefore have to endure days the equal of fourteen days on Earth. Therefore, Kepler wrote:
They feel insufferable heat. Perhaps they lack stone for erecting shelters against the sun. On the other hand, maybe they have a soil as sticky as clay. Their usual building plan, accordingly, is as follows. Digging up huge fields, they carry out the earth and heap it in a circle, perhaps for the purpose of drawing out the moisture down below. In this way, they may hide in the deep shade behind their excavated mounds and, in keeping with the sun’s motion, shift about inside, clinging to the shadow. They have, as it were, a sort of underground city. They make their homes in numerous caves hewn out of that circular embankment. They place their fields and pastures in the middle, to avoid being forced to go too far away from their farms in their flight from the sun.
Galileo’s jaw dropped as he read this. He was growing to dread the appearance of the word accordingly in Kepler’s work, a tic that always marked precisely the point where sequential logic was being tossed aside.
Then a few pages later, worse yet: Kepler spoke of the difference Galileo had noted through his spyglass between the light of the planets and that of the fixed stars: What other conclusion shall we draw from this difference, Galileo, than that the fixed stars generate their light from within, whereas the planets, being opaque, are illuminated from without; that is, to use Bruno’s terms, the former are suns, the latter, moons or earths?
Galileo groaned aloud. Just the sight of Bruno’s name in the same sentence as his own was enough to churn his stomach.
Then he came to a passage that made him go chill and hot at the same time. After Kepler’s congratulations for discovering the moons of Jupiter, and his ungrounded assertion that there must be a purpose for these new moons—and a false syllogism stating that, since the Earth’s moon existed for the pleasure of the people on Earth, the moons of Jupiter must exist to please the inhabitants of Jupiter, Kepler concluded that these inhabitants—
—must be very happy to behold this wonderfully varied display. The conclusion is quite clear. Our moon exists for us on the earth, not for the other globes. Those four little moons exist for Jupiter, not for us. Each planet in turn, together with its occupants, is served by its own satellites. From this line of reason we deduce with the highest degree of probability that Jupiter is inhabited.
Galileo threw this craziness to the floor with a curse and stalked out into his garden, wondering why his hilarity had so quickly turned to dread. “Kepler is some kind of idiot!” he shouted at Mazzoleni. “His reasoning is completely deranged! Inhabitants of Jupiter? Where the hell did that come from?”
And why was it so disturbing to read it?
The stranger … the man who had told him about the occhialino that afternoon in Venice … who had appeared after the great demonstration to the Venetian senate, and suggested he take a look at the moon—had he not said something about coming from Kepler? Quick flashes of something more—a blue like twilight—Had the stranger not come knocking at the gate one night some time ago? Had Cartophilus not joined the household soon after? What did all that mean?
Galileo was not used to having a vague memory of anything. Normally he would have said that he remembered basically everything that had ever happened to him, or that he had read or thought. That, in fact, he remembered too much, as quite a bit of what he recalled stuck in his brain like splinters of glass, stealing his sleep. He kept his thoughts busy partly in order not to be stuck by anything too sharp. But in this matter, clarity did not exist. There were blurs, as if he had been sick.