certain degree, against everything that might destroy or disorder it.
I perceive the very same things in the human machine, with this
difference, that nature alone operates in all the operations of the
beast, whereas man, as a free agent, has a share in his. One chooses
by instinct; the other by an act of liberty; for which reason the
beast cannot deviate from the rules that have been prescribed to it,
even in cases where such deviation might be useful, and man often
deviates from the rules laid down for him to his prejudice. Thus a
pigeon would starve near a dish of the best flesh-meat, and a cat on a
heap of fruit or corn, though both might very well support life with
the food which they thus disdain, did they but bethink themselves to
make a trial of it: it is in this manner dissolute men run into
excesses, which bring on fevers and death itself; because the mind
depraves the senses, and when nature ceases to speak, the will still
continues to dictate.

All animals must be allowed to have ideas, since all animals have
senses; they even combine their ideas to a certain degree, and, in
this respect, it is only the difference of such degree, that
constitutes the difference between man and beast: some philosophers
have even advanced, that there is a greater difference between some
men and some others, than between some men and some beasts; it is not
therefore so much the understanding that constitutes, among animals,
the specifical distinction of man, as his quality of a free agent.
Nature speaks to all animals, and beasts obey her voice. Man feels the
same impression, but he at the same time perceives that he is free to
resist or to acquiesce; and it is in the consciousness of this
liberty, that the spirituality of his soul chiefly appears: for
natural philosophy explains, in some measure, the mechanism of the
senses and the formation of ideas; but in the power of willing, or