And here I cannot help noticing the kindness of Providence in creating comets for the great relief of bewildered philosophers.  By their assistance more sudden evolutions and transitions are effected in the system of nature than are wrought in a pantomimic exhibition by the wonder-working sword of harlequin.  Should one of our modern sages, in his theoretical flights among the stars, ever find himself lost in the clouds, and in danger of tumbling into the abyss of nonsense and absurdity, he has but to seize a comet by the beard, mount astride of its tail, and away he gallops in triumph like an enchanter on his hippogriff, or a Connecticut witch on her broomstick, “to sweep the cobwebs out of the sky.”

It is an old and vulgar saying about a “beggar on horseback” which I would not for the world have applied to these reverend philosophers; but I must confess that some of them, when they are mounted on one of those fiery steeds, are as wild in their curvettings as was Phaeton of yore, when he aspired to manage the chariot of Phoebus.  One drives his comet at full speed against the sun, and knocks the world out of him with the mighty concussion; another, more moderate, makes his comet a kind of beast of burden, carrying the sun a regular supply of food and faggots; a third, of more combustible disposition, threatens to throw his comet like a bombshell into the world, and blow it up like a powder magazine; while a fourth, with no great delicacy to this planet and its inhabitants, insinuates that some day or other his comet—­my modest pen blushes while I write it—­shall absolutely turn tail upon our world and deluge it with water!  Surely, as I have already observed, comets were bountifully provided by Providence for the benefit of philosophers to assist them in manufacturing theories.

And now, having adduced several of the most prominent theories that occur to my recollection, I leave my judicious readers at full liberty to choose among them.  They are all serious speculations of learned men—­all differ essentially from each other—­and all have the same title to belief.  It has ever been the task of one race of philosophers to demolish the works of their predecessors, and elevate more splendid fantasies in their stead, which in their turn are demolished and replaced by the air-castles of a succeeding generation.  Thus it would seem that knowledge and genius, of which we make such great parade, consist but in detecting the errors and absurdities of those who have gone before, and devising new errors and absurdities, to be detected by those who are to come after us.  Theories are the mighty soap-bubbles with which the grown-up children of science amuse themselves while the honest vulgar stand gazing in stupid admiration, and dignify these learned vagaries with the name of wisdom!  Surely Socrates was right in his opinion, that philosophers are but a soberer sort of madmen, busying themselves in things totally incomprehensible, or which, if they could be comprehended, would be found not worthy the trouble of discovery.