names in the mouth of the generality that pronounce them.  There is in what they call nature and instinct a superior art and contrivance, of which human invention is but a shadow.  What is beyond all question is, that there are in beasts a prodigious number of motions entirely indeliberate, and which yet are performed according to the nicest rules of mechanics.  It is the machine alone that follows those rules:  which is a fact independent from all philosophy; and matter of fact is ever decisive.  What would a man think of a watch that should fly or slip away, turn, again, or defend itself, for its own preservation, if he went about to break it?  Would he not admire the skill of the artificer?  Could he be induced to believe that the springs of that watch had formed, proportioned, ranged, and united themselves, by mere chance?  Could he imagine that he had clearly explained and accounted for such industrious and skilful operation by talking of the nature and instinct of a watch that should exactly show the hour to his master, and slip away from such as should go about to break its springs to pieces?

Sect.  XXIV.  Of Food.

What is more noble than a machine which continually repairs and renews itself?  The animal, stinted to his own strength, is soon tired and exhausted by labour; but the more he takes pains, the more he finds himself pressed to make himself amends for his labour, by more plentiful feeding.  Aliments daily restore the strength he had lost.  He puts into his body another substance that becomes his own, by a kind of metamorphosis.  At first it is pounded, and being changed into a liquor, it purifies, as if it were strained through a sieve, in order to separate anything that is gross from it; afterwards it arrives at the centre, or focus of the spirits, where it is subtilised, and becomes blood.  And running at last, and penetrating through numberless vessels to moisten all the members, it filtrates in the flesh, and becomes itself flesh.  So many aliments, and liquors of various colours, are then no more than one and the same flesh; and food which was but an inanimate body preserves the life of the animal, and becomes part of the animal himself; the other parts of which he was composed being exhaled by an insensible and continual transpiration.  The matter which, for instance, was four years ago such a horse, is now but air, or dung.  What was then either hay, or oats, is become that same horse, so fiery and vigorous—­at least, he is accounted the same horse, notwithstanding this insensible change of his substance.

Sect.  XXV.  Of Sleep.