Isaac Newton (9 page)

He continued through dozens more axioms, comprising a logical whole, but a tangled one. He was hampered by the chaos of language—words still vaguely defined and words not quite existing. He conceived of
force
as a thing to be measured—but in what units? Was force inherent in bodies, as Descartes thought? Or was force an external agent, impinging on bodies and changing a differently named quantity:
quantity of motion; or quantity of mutation in its state
²⁷
; or
whole motion
; or
force of motion
? Whatever this missing concept was, it differed from velocity and direction. Axiom 100:

A body once moved will always keepe the same celerity, quantity and determination of its motion.
²⁸

At twenty-four, Newton believed he could marshal a complete science of motion, if only he could find the appropriate
lexicon, if only he could set words in the correct order. Writing mathematics, he could invent his own symbols and form them into a mosaic. Writing in English, he was constrained by the language at hand.
²⁹
At times his frustration was palpable in the stream of words. Axiom 103:

 … as the body (
a
) is to the body (
b
) so must the power or efficacy vigor strength or virtue of the cause which begets the same quantity of velocity.
…
³⁰

Power efficacy vigor strength virtue
—something was missing. But these were the laws of motion, in utero.

5
 
Bodys & Senses

H
E WAS LOOKING
inward as well as outward. Introspection told him that his imagination could see things as they really were. “Phantasie is helped,” he noted, “by good aire fasting moderate wine.” But it is also “spoiled by drunkenesse, Gluttony, too much study.” He added: from too much study, and from extreme passion, “cometh madnesse.”
¹

He wished to understand light itself—but did light’s essence lie outside or within the soul of the observer? In all the blooming perplexity of new philosophy, little was as muddled as the boundary between the perceived and the perceiver. Surely the mind, composed of pure thought, must have a point of contact with the body—at the pineal gland, Descartes proposed. The poet Andrew Marvell, graduate of Trinity College and now Member of Parliament for Hull, imagined the body and soul as enslaved, each by the other: “A soul hung up, as ’twere, in chains of nerves and arteries and veins.”
²
For Aristotle optics had been first a science not of light but of sight.

Newton, in his
Questiones
, had pondered the difficulty of understanding the senses, when those very senses were employed as the agents of understanding.

The nature of things is more securely & naturally deduced from their operations out upon another than upon our senses. And when by the former experiments we have found the nature of bodys, by the latter we may more clearely find the nature of our senses. But so long as we are ignorant of the nature of both soul and body we cannot clearly distinguish how far an act of sensation proceeds from the soul and how far from the body.
³

With this paradox in mind, Newton, experimental philosopher, slid a bodkin into his eye socket between eyeball and bone. He pressed with the tip until he saw “severall white darke & coloured circles.… Which circles were plainest when I continued to rub my eye with the point of the bodkin.” Yet when he held both eye and bodkin still, the circles would begin to fade.
⁴
Was light a manifestation of pressure, then?

Almost as recklessly, he stared with one eye at the sun, reflected in a looking glass, for as long as he could bear. He sensed that color—perhaps more than any of the other
qualities
of things—depends on “imagination and fantasy and invention.”
⁵
He looked away at a dark wall and saw circles of color. There was a “motion of spirits” in his eye. These slowly decayed and finally vanished. Were they real or phantasm? Could such colors ever be
real
, like the colors he had learned to make from crushed berries or
sheep’s blood? After looking at the sun, he seemed to perceive light objects as red and dark objects as blue. Strangely, he found that he could reproduce these effects, with practice, by pure, willful thought. “As often as I went into the dark & intended my mind upon them as when a man looks earnestly to see any thing which is difficult to be seen, I could make the phantasm return without looking any more upon the sun.”
⁶
He repeated the experiment until he began to fear permanent damage and shut himself up in a dark room. He remained there for three days; only then did his sight begin to clear.

(illustration credit 5.1)

Experiment—observation
—science
: these modern words were impressing themselves upon him. He read them in a new book from London, titled
Micrographia
: “The Science of Nature has been already too long made only a work of the Brain and the Fancy. It is now high time that it should return to the plainness and soundness of Observations on material and obvious things.”
⁷
The author was Robert Hooke, a brilliant and ambitious man seven years Newton’s senior, who wielded the microscope just as Galileo had the telescope. These were the instruments that penetrated the barrier of scale and opened a view into the countries of the very large and the very small. Wonders were revealed there. The old world—the world of ordinary scales—shrank into its place in a continuum, one order among many. Like Galileo, Hooke made meticulous drawings of strange new sights and popularized his instrument as a curiosity for wealthy aristocrats—though, after they bought the device from the lens shop in London where he sometimes worked, they rarely succeeded in seeing anything but vague shadows. Hooke was Newton’s inspiration now (though Newton
never acknowledged that). He became Newton’s goad, nemesis, tormentor, and victim.

Hooke had a unique post. He was employed, if seldom actually paid, as Curator of Experiments to a small group of men who formed, in 1662, what they called the Royal Society of London. They meant to be a new sort of institution: a national society dedicated to promoting—and especially “communicating”—what they called “the New Philosophy” or “Experimental Philosophy.”
⁸
Amazing discoveries warranted this banner: comets and new stars; the circulation of the blood; the grinding of glasses for telescopes; the possibility of vacuities (and nature’s abhorrence thereof); the descent of heavy bodies; and diverse other things.
⁹

Nullius in verba
was the Royal Society’s motto. Don’t take anyone’s word for it.
¹⁰
These gentlemen had begged for and received the king’s patronage, but patronage meant good will only; the society collected from its members a shilling at a time and strained to find meeting places. Among the founders was John Wilkins, author of
The Discovery of a New World
a generation before. If one man was their muse, he was the late Francis Bacon, who had written:

We must … completely resolve and separate Nature, not by fire, certainly, but by the mind, which is a kind of divine fire.… There will remain, all volatile opinions vanishing into smoke, the affirmative form, solid, true and well-defined. Now this is quickly said, but it is only reached after many twists and turns.
¹¹

The twists and turns became the responsibility of the Curator of Experiments, Hooke, technician and impresario.
He demonstrated experiments with air-pumps. At one meeting he cut open the thorax and belly of a living dog, observed its beating heart, and used a bellows to inflate its lungs in an experiment on respiration, which he later felt reluctant to repeat “because of the torture of the creature.”
¹²
Another meeting dazzled and confused the Duchess of Newcastle with colors, magnets, microscopes, roasted mutton, and blood.
¹³
This was all science, a new spirit and almost a method: persuasion from practical experience, and formalized recording of data. Hooke lacked mathematics but not ingenuity. He invented or improved barometers, thermometers, and wind gauges, and he tracked London weather obsessively.
¹⁴

In
Micrographia
he displayed the “new visible world” to be seen through the instrument he described as an artificial organ. “By the help of Microscopes, there is nothing so small, as to escape our inquiry,” he declared.
¹⁵
As a geometer begins with a mathematical point, he examined the point of a needle—perfectly sharp, yet under the microscope, blunt and irregular. By analogy he suggested that the earth itself, seen from a great enough distance, would shrink to a scarcely visible speck. More specks were to be found in printed books: he proceeded to study and draw the mark of a full stop, the punctuation mark—again surprisingly rough and irregular, “like a great splatch of London dirt.”
¹⁶
He found wonderment in the edge of a razor and the weft of fine linen. He discovered shifting, iridescent colors in thin flakes of glass. He knew that Descartes had seen a rainbow of colors in light passed through a prism or a water drop, and he compared microscopic rainbows.

And here he made his book something more than a registry
and gazetteer for his new world. He notified readers that he offered a
theory
—a complete and methodical explanation of light and color. Aristotle had thought of color as a commingling of black and white. His followers considered colors fundamental qualities of matter, carried by light into the eye. Descartes had speculated that color came from globules of light changing speed when refracted by glass or water. Hooke disputed this and, grandly invoking the shade of Bacon, turned to experiment: an “
Experimentum Crucis
, serving as Guide or Land-mark.”
¹⁷
True, Hooke observed, a prism produces colors when refracting light. But he asserted that refraction was not necessary. His landmark was the production of color in transparent substances:
¹⁸
“for we find, that the Light in the open Air, either in or out of the Sun-beams, and within a Room, either from one or many Windows, produces much the same effect.”

Light is born of motion, he argued. “That all kind of
fiery burning Bodies
have their parts in motion, I think will be very easily granted me.” Sensing more than he could truly see, he asserted that all luminous bodies are in motion, perhaps vibrating: sparks, rotting wood, and fish. Further, he observed, or thought he observed, that two colors were fundamental: blue and red. They were caused by “an impression on the retina of an oblique and confus’d pulse of light.”
¹⁹
Where red and blue “meet and cross each other,” the imperfection generated “all kinds of greens.” And here his theory ended. “It would be somewhat too long a work for this place zetetically to examine, and positively to prove, what particular kind of motion it is.… It would be too long, I say, here to insert the discursive progress by which I inquir’d after the properties of the motion of Light.…”
²⁰