WHEN THE STARS BEGAN TO SPEAK
What was it that Galileo saw when he looked through the telescope? What was it that led him to come upwith that "profoundly new idea" that the underlying reality is a ceaseless flow of light?
It was the Moon he turned to first. For endless hours, indeed through endless weeks, Galileo sat rapt at the eyepiece of his telescope, gazing at the continents overhead, watching the endless play of light and shadow as daybreak crept across them, as the cloudless lunar morning drew to a cloudless lunar noon; watching as the Moon waxed to full, and then waned again, and the ragged edge of twilight pursued the vanished edge of dawn around the face of Earth's silent sister.
What was it that the Moon had to reveal? What glued Galileo to that awesome sight?
"On the fourth or fifth day after the new moon," he wrote in the Sidereus Nuncus.
"when the Moon is seen with brilliant horns, the boundary which divides the dark part from the light does not extend across the Moon in a smooth oval line, as it would on a perfectly spherical solid; rather, it traces out an uneven, rough, and very wavy line.
"A great number of small blackish spots, entirely separated from the dark region of the Moon, are scattered about at this time in the area illumined by the Sun. I have reason to believe that these are valleys still in shadow in the early lunar morning; for let us note that, always, these small dark spots have their darkest parts on the side nearest to the Sun, while on the side opposite the Sun they are crowned with bright contours, like shining summits. There is a similar sight on Earth about sunrise, when we behold the valleys not yet flooded with light, though the mountains surrounding them are already ablaze with glowing splendor on the side opposite the Sun. And just as the shadows in the hollows on Earth diminish in size as the Sun rises higher, so these spots on the Moon lose their blackness, and dwindle, as the illuminated region grows larger and larger.
… Still more astonishingly, many bright points appear within the darkened portion of the Moon, completely separate from the illuminated part and at a considerable distance from it. After a time they gradually increase both in size and in brightness; and an hour or two later they become joined onto the rest of the lighted part of the Moon, which has now increased in size.
"Meanwhile more and more peaks shoot up, as if sprouting, now here, now there, lighting up within the shadowed portion. These become larger, and at length they too are united to that same luminous surface, which now extends ever further …
"And on Earth, before the rising of the Sun, are not the highest peaks of the mountains lit by the Sun's rays while yet the plains remain in shadow? Does not the light go on spreading while the larger trunks of those mountains are becoming illumined? And when the Sun at - has risen, does not the illumination of plains and hills become one at last?
For centuries Earth's finest scholars had argued: Some said that the Moon is a flat and polished disk, like an enormous plate, pasted onto the transparent sphere, the "lunar orb" ("orb" as in "orbit") that enclosed the Earth like an eggshell and held the Moon in place. Other scholars, equally erudite, declared that the Moon is a great and perfectly polished sphere of changeless and imperishable crystal, set by God among the heavens on the fourth day of Creation. And still other learned men, a tiny minority in the long dispute, avowed that the Moon is polished but concave in shape, like a bowl with the hollow side facing our eyes.
But mountains and valleys on the Moon??! What Galileo saw through his telescope went against all the conclusions of two thousand years of ignorant philosophizing by "learned" men!
Heaven, said the philosophers, is where God lives, where good people go when they die: there is no sickness or death up there- no accidents - no imperfections - no changes and no suffering. And the Moon is up in Heaven - so, naturally, the Moon will partake of the character of Heaven. It will not be marred, as our planet Earth is marred, by accidents or imperfections, like mountains and chasms; for while our planet Earth is made of the four lower essences - earth, air, fire, and water - all of which are subject to corruption - the Moon, like everything else in Heaven, is made of the fifth essence, the quintessence, which is eternally incorruptible. And therefore the Moon will be perfect as Heaven is perfect perfectly flat, or perfectly rounded made of some substance that will never chip or crack, like some ultimate miracle-plastic kitchen utensil.
Everyone agreed that this was beautiful philosophy, and the proper way to think about the Moon.* Skilled university orators had made speeches to Galileo's class in his student days at the University of Pisa, comparing the quintessence, the heavenly perfection of the Moon, to the essence and perfection of the diamond, which is flawless and clear and limpid as pure water, and
* It is easier to imagine physical perfection then it is to imagine spiritual perfection. This explains this strange conception of the Moon. It explains why people talk about Heaven in terms of pearly gems, streets flowing with Milk and Honey, and angels playing harps. And it also explains the search for the Fountain of Youth, the search for the Seven Cities of Gold, the search for the perfect suburban address - and the people who are shocked if their Savior catches cold …
sparkles with a silvery light most pleasing to the eye, and cannot be scratched by any other substance on account of its great hardness, and is precious in the eyes of men. Others had compared the Moon to a mathematically perfect sphere of silver, which resists the attack of acids better than any other metal except gold itself. … Here on Earth, the cosmologers agreed, the Devil injures things, and sins corrupt; but in Heaven, where the Moon is, the Devil has never had a chance to wreak corruption. Heaven is untouched by Adam's fall. Without a telescope, anyone could "see" that the heavens were changeless. On Earth, cities are built and razed, but has anyone ever seen stars blink into and out of existence in the sky? Of course not! And why not? Because in Heaven all things partake of the changeless, pure, and immutable nature of the Word of God, which reigns there supreme. As the prophet Isaiah says: The grass withers, and the flower fades. but the Word of God endureth forever …
Unfortunately for lazy philosophers, new stars had blinked into existence in the sky, and very recently too. In 1572, when Galileo was 8 years old, a new star had flowered in Cassiopeia, a supernova of such brilliance that for several weeks it had been visible in broad daylight. Another new star had appeared in 1604, just six years before the Siderius Nuncius, and Johannes Kepler had published a penetrating essay about it which was titled De Stella Nova in Pede Serpentarii-"About the New Star in the Foot of the Serpent-Bearer" The learned speechmakers, who drew so many artful conclusions from the supposed "changelessness" of the heavens, had done their best to ignore the new stars. This made Galileo thoughtful. He had always suspected that these speechmakers were mostly pompous fools, over-educated men who mouthed cliches to hide their lack of understanding. Their steadfast refusal to learn from the new stars was like the proverbial thirteenth stroke of a clock: not only false in itself, but something that cast grave doubts on the validity of all the strokes the clock had ever rung. Galileo remembered what Pythagoras had said about motion and change: Everything moves; everything is alive. Surely, thought Galileo, this Word of God - the Breath that gave life to Adam, the Spirit that lent eloquence to the tongues of the Apostles at the Pentecost - surely this Word must be more than a mere device to keep the heavens from changing and decaying, like the ice poured over a dead fish! In Galileo's own words -
"I cannot, without great astonishment, and even a sense of disbelief, hear people say that the changelessness of certain natural bodies is a great perfection and nobility on their part, or that the alterable, generable, mutable nature of other natural bodies is a grave defect.
"For my own part, I consider this planet Earth very noble and admirable precisely because of the many and diverse changes, alterations, and generations that occur in it incessantly. And if, not being subject to any change,this planet had been created as a vast desert of sand or a mountain of jade - or if, at the time of the Flood, the waters which covered the globe had frozen, converting it into an enormous crystalline sphere of ice where nothing was ever born or died or grew or altered or changed - why, then, I should have considered the Earth to be a wretched lump, of no benefit to the Universe, a mass of idleness, and in a word superfluous. … The difference is exactly that which lies between a living body and a dead body; and I say the same of the Moon, of Jupiter, and of all the other globes in the Universe.
"The more I delve in my ponderings into the vanities of popular discourses, the more empty and foolish I find them. What greater folly can be imagined than to call jewels, silver and gold 'noble', and earth and topsoil 'base? People who do this ought to consider that if there were as great a scarcity of dirt as there is of jewels and precious metals, there would not be a king in all the world who would not gladly give a bushel of diamonds and rubies and a cartload of gold, just to buy enough dirt to plant a jessamine or tangerine in a little pot, that he might watch it sprout from a seed, and grow, and bring forth goodly leaves and fragrant flowers and delicate fruit.
"It is scarcity that makes a thing precious to the vulgar; it is commonness that makes them de- spise a thing. They will say that a diamond is beautiful because it is as clear as pure water, but they will not parr with one for ten tons of water.
"These men who so extol incorruptibility, inalterability, and so forth, speak thus, I believe, out of their great desire to live forever without having to change, and for fear of death. It never occurs to them that, if the life of men was eternal and changeless, not only death but birth alsowould not exist, and they would never have been born into the world to begin with. Such people deserve to meet with a Medusa's head, which would transform them into statues of diamond and jade, and thus make them more perfect than they are."
And now, as the peaks of the lunar Apennines caught the first glint of sunlight in the lunar dawn, and as the light spread slowly down their flanks until only the lunar valleys were still hidden in pools of shadow, until at - the Sun, bursting over the spreading arms of the mountains, bathed even the valleys in clear light, Galileo, seeing this incredible spectacle through his "eyeglass", did not feel distressed, as so many of the learned scholars and theologians would have felt in his place, by the Moon's defiance of the accepted theories of the heavens. The mountains were there, the valleys were there; they could not be argued away - and therefore the processes of mountain-building and erosion must also be up there. And therefore the indestructible "Word of God", which reigns unchallenged in Heaven, could not possibly be merely a divine embalming fluid. On the contrary; if the Word of God does reign unchallenged in Heaven, then it must be the thing that makes things change - the indestructible essence of change-the essence of life-the ultimate reality - the ceaseless surge and flow of light. And that is a thing that reigns on Earth as well.
How could anyone deny it? Here was the evidence, standing before us in the skies! Here was the Moon, riding in God's Heaven, with a face not very different from God's Italy!
Galileo was 45 years old at the time that his Sidereus Nuncius was published. After 45 years, at last he had found his purpose. He set out, unafraid of the risks, to share his new-found truths with the world.