vation. There is not, perhaps, a human being, of
ordinary education and of average reflective capacity, to whom, at some
period, the fancy in question has not occurred, as if spontaneously, or
intuitively, and wearing all the character of a very profound and very
original conception. This conception, however, so commonly entertained,
has never, within my knowledge, arisen out of any abstract
considerations. Being, on the contrary, always suggested, as I say, by
the vorticial movements about centres, a reason for it, also,--a _cause_
for the ingathering of all the orbs into one, _imagined to be already
existing_, was naturally sought in the same direction--among these cyclic
movements themselves.

Thus it happened that, on announcement of the gradual and perfectly
regular decrease observed in the orbit of Enck's comet, at every
successive revolution about our Sun, astronomers were nearly unanimous
in the opinion that the cause in question was found--that a principle was
discovered sufficient to account, physically, for that final, universal
agglomeration which, I repeat, the analogical, symmetrical or poetical
instinct of Man had predetermined to understand as something more than a
simple hypothesis.

This cause--this sufficient reason for the final ingathering--was declared
to exist in an exceedingly rare but still material medium pervading
space; which medium, by retarding, in some degree, the progress of the
comet, perpetually weakened its tangential force; thus giving a
predominance to the centripetal; which, of course, drew the comet nearer
and nearer at each revolution, and would eventually precipitate it upon
the Sun.

All this was strictly logical--admitting the medium or ether; but this
ether was assumed, most illogically, on the ground that no _other_ mode
than the one spoken of could be discovered, of accounting for the
observed decrease in the orbit of the comet:--as if from the fact that we
could _discover_ no other mode of accounting for it, it followed, in any
respect, that no other mode of accounting for it existed. It is clear
that innumerable causes might operate, in combination, to diminish the
orbit, without even a possibility of our ever becoming acquainted with
one of them. In the meantime, it has never been fairly shown, perhaps,
why the retardation occasioned by the skirts of the Sun's atmosphere,
through which the comet passes at perihelion, is not enough to account
for the phaenomenon. That E