Part One: The Systematic Constitution of the Fixed Stars

Preface

I have chosen a subject which, by its inner difficulty and also with regard to religion, may at first arouse an unfavourable prejudice in many readers. To discover the systematic element that binds together the great members of creation in the whole extent of infinity; to derive the formation of the heavenly bodies themselves, and the origin of their motions, from the first state of nature by mechanical laws — such insights seem to go far beyond the powers of human reason.

And religion threatens with a solemn accusation the boldness that would dare to ascribe to nature, left to itself, consequences in which one rightly sees the immediate hand of the Supreme Being; and it is afraid of finding in the impertinence of such reflections a defence of the atheist.

Kant answers that if matter, following its own laws, produces order and beauty, this proves not that there is no God, but that matter itself is bound by laws that point to a supreme wisdom. He distinguishes his view from the chance atoms of Epicurus and Lucretius.

Matter, which is the original material of all things, is bound to certain laws; and, freely left to these laws, it must necessarily bring forth beautiful combinations. It has no freedom to deviate from this plan of perfection. Since it is thus subject to a supremely wise purpose, it must necessarily have been placed into such harmonious relations by a first cause ruling over it; and there is a God precisely because nature, even in chaos, cannot proceed otherwise than regularly and in order.

Give me matter, and I will build a world out of it! That is: give me matter, and I will show you how a world is to arise from it.

"Gebet mir Materie, ich will eine Welt daraus bauen!" — the most famous line of the book. Kant adds at once that one cannot say the same of the smallest plant or caterpillar: "Give me matter, and I will show you how a caterpillar can be produced?" Here, he admits, we stumble at the first step.

A Short Sketch of Newton's Philosophy

The six planets, three of which have satellites — Mercury, Venus, the Earth with its moon, Mars, Jupiter with four, and Saturn with five satellites — which describe circles around the sun as their centre, together with the comets, which do so from all sides and in very elongated orbits, make up a system called the solar system, or the planetary world. The motion of all these bodies is governed by two forces: attraction towards the sun, and a sideways, "shooting" force, which makes them circle rather than fall.

In 1755 only six planets were known; Uranus was discovered in 1781.

All the planets move in the same direction, and in nearly the same plane — that of the sun's equator. This common direction and plane are a sign, Kant argues, that they share a common origin.

The Milky Way and the Nebulae

Kant builds on the ideas of Thomas Wright of Durham, an English writer whose "Original Theory of the Universe" (1750) he knew from a review. If one looks at the starry sky on a clear night, one sees a broad band of light, the Milky Way, crossing the sky. This band is not a mere accident: the stars are concentrated in a plane, like the planets of the solar system. Our sun is one of these stars, and we look out from within the disc; looking along the plane, we see the stars crowded together into the Milky Way; looking out from it, we see them scattered.

The fixed stars, then, form a system — a flattened disc, held together by the same gravitation that holds the planets, and probably rotating, though so slowly that no one has yet observed it.

This picture of the Milky Way as a rotating disc of stars, with the sun inside it, is in its broad outlines correct.

And further: the faint, elliptical patches of light that astronomers call nebulae — such as the one Maupertuis described — are probably not single stars or clouds within our system, but other Milky Ways: other systems of stars, so far away that their stars merge into a faint glow. Seen face-on they would appear round; seen at an angle, elliptical. These higher orders of systems are themselves, perhaps, members of yet greater systems, without end.

This idea — later called "island universes" — was confirmed only in the 1920s, when Edwin Hubble showed that the Andromeda nebula is a separate galaxy far beyond the Milky Way.

Here the understanding loses itself in the immeasurable. It sees systems of worlds, and systems of systems, extending without limit — a field that the boldest imagination cannot exhaust.