SECT.  XXV.  Of Sleep.

The natural attendant of food is sleep; in which the animal forbears not only all his outward motions, but also all the principal inward operations which might too much stir and dissipate the spirits.  He only retains respiration, and digestion; so that all motions that might wear out his strength are suspended, and all such as are proper to recruit and renew it go on freely of themselves.  This repose, which is a kind of enchantment, returns every night, while darkness interrupts and hinders labour.  Now, who is it that contrived such a suspension?  Who is it that so well chose the operations that ought to continue; and, with so just discernment, excluded all such as ought to be interrupted?  The next day all past fatigue is gone and vanished.  The animal works on, as if he had never worked before; and this reviving gives him a vivacity and vigour that invites him to new labour.  Thus the nerves are still full of spirits, the flesh smooth, the skin whole, though one would think it should waste and tear; the living body of the animal soon wears out inanimate bodies, even the most solid that are about it; and yet does not wear out itself.  The skin of a horse, for instance, wears out several saddles; and the flesh of a child, though very delicate and tender, wears out many clothes, whilst it daily grows stronger.  If this renewing of spirits were perfect, it would be real immortality, and the gift of eternal youth.  But the same being imperfect, the animal insensibly loses his strength, decays and grows old, because everything that is created ought to bear a mark of nothingness from which it was drawn; and have an end.