proof that it could not consist of stars; but now that it has been resolved, we are entitled to conclude that in nebulæ, such as the spiral ones, where there is the appearance of motion, the spirals are not purely nebulous matter thrown off from the nucleus like water twirled from a mop, or by any spiral movement whatever.

As the appearance of motion, therefore, in particular nebulæ, is no proof that they consist of purely nebulous matter composed of invisible particles, we are entitled to draw the conclusion that this large class of celestial bodies are clusters of stars at an immense distance from our own system, that each of the stars of which they are composed is the sun or centre of a system of planets, and that these planets are inhabited, or if we follow a strict analogy, that at least one planet in each of these numberless systems, is like our earth, the seat of vegetable, animal, and intellectual life.

Before we quit the subject of nebulæ, and purely nebulous matter, we must notice two points connected with the optical appearance of nebula, which we think are strong arguments in favour of their being resolvable into stars. If

a nebula consisted of phosphorescent or self-luminous atoms of nebulous matter, its light would be immensely inferior in brightness to that of the same nebula composed of suns which are provided with a luminous atmosphere for the very purpose of discharging a brilliant light. When we see, therefore, two nebulæ of the very same brightness, and find by the telescope that one of them only is resolvable into stars, we can scarcely doubt that the other is similarly composed. We cannot conceive that a nebula of phosphorescent stars could be visible at such enormous distances from our system. When a planetary nebula is equally bright in every part of its disc, like that which is a little to the south of B Ursa Majoris, and which resembles a flat disc, " presented to us in a plane precisely perpendicular to the visual ray," it is impossible to regard it as nebulous matter in a state of aggregation. In like manner, all those nebulæ, which have strange and irregular shapes, indicate the absence of any force of aggregation, and authorize us to regard them as clusters of stars.

M

CHAPTER X.

GENERAL SUMMARY.

THE arguments for a plurality of worlds, contained in the preceding chapters, are so various, and have such different degrees of force, that different views of the subject will be taken by persons who thoroughly believe in the general doctrine. We can easily conceive why some persons may believe that all the planets which have satellites are inhabited, while they deny the inhabitability of those that have none, and also of the Sun and the satellites themselves. There are individuals, too, though we doubt their faith in sidereal astronomy, who readily believe that the whole of our planetary system is the seat of life, while they are startled by the statement that every star in the heavens, and every point in a nebula which the most powerful telescope has not separated from its neigh

bour, is a sun surrounded by inhabited planets like our own; and that immortal beings are swarming through universal space more numerous than drops of water in the ocean, or the grains of sand upon its shores. But if these persons really believe in the distances and magnitudes of the stars, and of the laws which govern the binary systems of double stars, they must find it equally, if not more difficult to comprehend, why innumerable suns and worlds fill the immensity of the universe, revolving round one another, and discharging their light and heat into space, without a plant to spring under their influence, without an animal to rejoice in their genial beams, and without the eye of reason to lift itself devoutly to its Creator. In peopling such worlds with life and intelligence, we assign the cause of their existence; and when the mind is once alive to this great truth, it cannot fail to realize the grand combination of infinity of life with infinity of matter.

In support of these views, we have already alluded to the almost incredible fact, that there are in our own globe hills and strata miles in length, composed of the fossil remains of micro

scopic insects; and we need scarcely remind the least informed of our readers, that the air which they breathe, the water which they drink, the food which they eat, the earth on which they tread, the ocean which encircles them, and the atmosphere above their heads, are swarming with universal life. Wherever we have seen matter we have seen life. Life was not made for matter, but matter for life; and in whatever spot we see its atoms, whether at our feet, or in the planets, or in the remotest star, we may be sure that life is there-life to enjoy the light and heat of God's bounty-to study His works, to recognise His glory, and to bless His name.

Those ungenial minds that can be brought to believe that the Earth is the only inhabited body in the universe, will have no difficulty in conceiving that it also might have been without inhabitants. Nay, if such minds are imbued with geological truth, they must admit that for millions of years the Earth was without inhabitants; and hence we are led to the extraordinary result, that for millions of years there was not an intelligent creature in the vast do