work, the celebrated philosopher Christian Huygens, the contemporary of Newton, and the discoverer of the ring and one of the satellites of Saturn, composed a work on the Plurality of Worlds, under the title of the Theory of the Universe, or Conjectures concerning the Celestial Bodies and their Inhabitants.1 This interesting treatise, as large as that of Fontenelle, was translated into English, and went through at least two editions. It was written at the age of sixty-seven, a short time before the author's death; and so great was the interest which he felt in its publication, that he earnestly besought his brother to carry his wishes into effect. He mentions the great pleasure he had derived from the composition of it, and from the communication of his views to his friends. About to enter the world of the future, the philosopher who had added a new planet to our system, and discovered the most magnificent and incomprehensible of its structures,

1 Cosmotheoros, sive de Terris Celestibus, earumque ornatu, conjecturæ, ad Constantinum Hugenium Fratrem, Gulielmo iii. Magne Britanniæ Regi a Secretis. Hugenii Opera, tom. ii. pp. 645-722.

2 The Celestial Worlds Discovered, or Conjectures concerning the Inhabitants, Plants, and Productions of the Worlds in the Planets. The second edition, corrected and enlarged. London, 1722. The first edition seems to have been published in 1698. Two French editions of the Cosmotheoros were published, one in Paris, in 1702, the other at Amsterdam, in 1718.

looked forward with a peculiar interest to a solution of the mysteries which it had been the business and the happiness of his life to contemplate. He was anxious that his fellow-men should derive the same pleasure that he did, from viewing the planets and the stars as the seats of intellectual life, and he left them his Theory of the Universe-a legacy worthy of his name.

The Cosmotheoros is a work essentially different from that of Fontenelle. It is didactic and dispassionate, deducing by analogical reasoning a variety of views respecting the plants and animals in the planets, and the general nature and condition of their inhabitants. The work is to some extent a popular Treatise on Astronomy, and contains all that was at that time known respecting the primary and secondary planets of the solar system.

We are not acquainted with any other work written expressly on the subject of a Plurality of Worlds, but the doctrine was maintained by almost all the distinguished astronomers and writers who have flourished since the true figure of the earth was determined. Giordano Bruno of Nola,1 Kepler and Tycho believed in it; and Cardinal Cusa and Bruno, before the discovery of binary systems

1 In his work entitled Universo e Mondi innumerabili.

among the stars, believed also that the stars were inhabited. Sir Isaac Newton likewise adopted it, and Dr. Bentley, Master of Trinity College, Cambridge, in his eighth sermon on the Confutation of Atheism from the origin and frame of the world,1 has ably maintained the same doctrine. In our own day we may number among its supporters the distinguished names of the Marquis De Laplace, Sir William and Sir John Herschel, Dr. Chalmers, Isaac Taylor, and M. Arago.

After the publication of Dr. Chalmers's Astronomical Discourses, in which the doctrine of a Plurality of Worlds was maintained with much eloquence and force of argument, an attempt to reply to it was made by a Mr. Alexander Maxwell, a London publisher, in a work which, though entitled Plurality of Worlds, contains only one chapter on the subject. This volume, a second edition of which was published in 1820, is written by a person who does not believe in the grand truths of Astronomy, and who regards the Newtonian philosophy as containing principles "which lie at the foundation of all atheistical systems," and which are not only absurd

This sermon was written from the information given him by Sir Isaac Newton in his four celebrated letters addressed to Dr. Bentley.

but dangerous," instilling a destructive poison into the human heart!"

Under these circumstances the scientific world has been greatly surprised at the appearance of a work entitled Of the Plurality of Worlds, the object of which, like that of Maxwell, is to prove that our earth is the only inhabited world in the universe, while its direct tendency is to ridicule and bring into contempt the grand discoveries in sidereal astronomy by which the last century has been distinguished. Although it is not probable that a work of this kind, however ably it is written, and however ingenious be the reasoning by which views so novel and extraordinary are maintained, will influence opinions long and deeply cherished, we have thought it necessary, in support of astronomical truth, as well as of the lessons which it teaches, to defend the doctrine of a Plurality of Worlds by the aid of modern discoveries, and to analyze and refute the objections which have been made to it in the work to which we have referred.

CHAPTER I.

RELIGIOUS ASPECT OF THE QUESTION.

EFORE Christianity shed its light upon the

BEFO

world, the philosopher who had no other guide but reason, looked beyond the grave for a resting-place from his labours, as well as for a solution of the mysteries which perplexed him. Minds, too, of an inferior order, destined for immortality, and conscious of their destination, instinctively pried into the future, cherishing visions of another world with all the fervour of domestic affection, and with all the curiosity which the study of nature inspires. Interesting as has been the past history of our race,engrossing as must ever be the present,-the future, more exciting still, mingles itself with every thought and sentiment, and casts its beams of hope, or its shadows of fear, over the stage both of active and contemplative life. In youth we scarcely descry it in the distance. To the stripling and the man it