It is well known there have been, to the metaphysical head, difficulties almost insuperable as to How, in the System of Nature, Motion is? How, in the name of wonder, it can be; and even, Whether it is at all? Difficulties to the metaphysical head, sticking its nose into the gutter there;--not difficult to my readers and me, who can at all times walk across the room, and triumphantly get over them. But stick your nose into any gutter, entity, or object, this of Motion or another, with obstinacy,--you will easily drown, if that be your determination!--Suffice it for us to know in this matter, that Maupertuis, intensely watching Nature, has discovered, That the key of her enigma (or at least the ultimate central DOOR, which hides all her Motional enigmas, the key to WHICH cannot even be imagined as discoverable!) is, that "Nature is superlatively THRIFTY in this affair of motion;" that she employs, for every Motion done or do-able, "a MINIMUM OF ACTION;" and that, if you well understand this, you will, at least, announce all her procedures in one proposition, and have found the DOOR which leads to everything. Which will be a comfort to you; still looking vainly for the key, if there is still no key conceivable. Perpetual President Maupertuis, having surprised Nature in this manner, read Papers upon it to an Academy listening with upturned eyes; new Papers, perfected out of old,--for he has long been hatching these Phoenix-eggs; and has sent them out complete, quite lately, in a little Book called COSMOLOGIE, where alone I have had the questionable benefit of reading them. Grandly brief, as if coming from Delphi, the utterance is; loftily solemn, elaborately modest, abstruse to the now human mind; but intelligible, had it only been worth understanding:--a painful little Book, that COSMOLOGIE, as the Perpetual President's generally are. "Minimum of Action, LOI D'EPARGNE, Law of Thrift," he calls this sublime Discovery;--thinks it will be Sovereign in Natural Theology as well: "For how could Nature be a Save-all, without Designer present?"--and speaks, of course, among other technical points, about "VIS VIVA, or Velocity multiplied by the Square of the Time:" which two points, "LOI D'EPARGNE," and that "the VIS VIVA is always a Minimum," the reader can take along with him; I will permit him to shake the others into Limbo again, as forgettable by human nature at this epoch and henceforth.