t once to the conclusion that the whole of our
firmament was at one time a diffused mass of nebulous matter,
extending through the space which it still occupies. So also, of
_course_, must have been the other astral systems. Indeed, we must
presume the whole to have been originally in one connected mass,
the astral systems being only the first division into parts, and
solar systems the second.

"The first idea which all this impresses upon us is, that the
formation of bodies in space is _still and at present in progress_.
We live at a time when many have been formed, and many are still
forming. Our own solar system is to be regarded as completed,
supposing its perfection to consist in the formation of a series of
planets, for there are mathematical reasons for concluding that
Mercury is the nearest planet to the sun, which can, according to
the laws of the system, exist. But there are other solar systems
within our astral systems, which are as yet in a less advanced
state, and even some quantities of nebulous matter which have
scarcely begun to advance towards the stellar form. On the other
hand, there are vast numbers of stars which have all the appearance
of being fully formed systems, if we are to judge from the complete
and definite appearance which they present to our vision through
the telescope. We have no means of judging of the _seniority of
systems; but it is reasonable to suppose that among the many, some
are older than ours_. There is, indeed, one piece of evidence for
the probability of the comparative youth of our system, altogether
apart from human traditions and the geognostic appearances of the
surface of our planet. This consists in a thin nebulous matter,
which is diffused around the sun to nearly the orbit of Mercury, of
a very oblately spheroidal shape. This matter, which sometimes
appears to our naked eyes, at sunset, in the form of a cone
projecting upwards in the line of the sun's path, and which bears
the name of the Zodiacal Light, has been thought a residuum or last
remnant of the concentrating matter of our system, and thus may be
supposed to indicate the comparative recentness of the principal
events of our cosmogony. _Supposing the surmise and inference_ to
be correct, and they may be held as so far supported by more