with which we are acquainted on earth is the
velocity of light, which travels a million of times faster than a
cannon-ball, or at the rate of 195,000 miles per second; but here is a
substance capable of traveling twenty-three times faster, and here is a
force propelling it, twenty-three times greater than any which exists on
earth. Its existence was first discovered by the coruscations of the
comet of 1807. "In less than one second, streamers shot forth, to two
and a half degrees in length; they as rapidly disappeared, and issued
out again, sometimes in proportions, and interrupted, like our northern
lights. Afterward the tail varied, both in length and breadth; and in
some of the observations, the streamers shot forth from the whole
expanded end of the tail, sometimes here, sometimes there, in an
instant, two and a half degrees long; _so that within a single second
they must have shot out a distance of 4,600,000 miles_."[215] Similar
exhibitions of this unknown force were made by the comet of 1811, by
Halley's comet, and several others.

In these amazing disclosures of the unknown forces of the heavens, do we
not hear a voice rebuking the presumption of ignorant theorists, with
the questions, Knowest _thou_ the ordinances of heaven? Canst _thou_ set
the dominion thereof in the earth? Hear one of the most distinguished of
modern astronomers expound the moral bearings of such a discovery: "The
intimation of a new cosmical power--I mean of one so unsuspected before,
but which yet can follow a planet through all its wanderings--throws us
back once more into the indefinite obscure, and checks all dogmatism.
How many influences, hitherto undiscovered by our ruder senses, may be
ever streaming toward us, and modifying every terrestrial action. And
yet, because we had traced one of these, we have deemed our astronomy
complete! Deeper far, and nearer to the root of things, is that world
with which man's destiny is entwined."[216]

We can have no reason, save our own self-sufficient arrogance, to
believe that the discovery of these two forces exhausts the treasures of
infinite wisdom. Humboldt thus well refutes the folly of such an
imagination: "The imperfectibility of all empirical science, and the
boundlessness of the sphere of observation, render the task of
explaining the forces of matter by that which is variable in matter, an
impracticable one. What has been already perceived, by no means exhausts
that which is perceptib