t of
thought, appeared, the physician La Mettrie[1] (1709-51) had promulgated
materialism, though rather in an anthropological form than as a
world-system, and with cynical satisfaction in the violation of traditional
beliefs--in his _Natural History of the Soul_, 1745, in a disguised form,
and, undisguised, in his _Man a Machine_, 1748--and at the same time
(_Anti-Seneca, or Discourse on Happiness_, 1748) had sketched out for
Helvetius the outlines of the sensationalistic morality of interest. While
ill with a violent fever he observed the influence of the heightened
circulation of the blood on his mental tone, and inferred that thought is
the result of the bodily organization. The soul can only be known from the
body. The senses, the best philosophers, teach us that matter is never
without form and motion; and whether all matter is sentient or not,
certainly all that is sentient is material, and every part of the organism
contains a vital principle (the heart of a frog beats for an hour after
its removal from the body; the parts of cut-up polyps grow into perfect
animals). All ideas come from without, from the senses; without
sense-impressions no ideas, without education, few ideas, the mind of a man
grown up in isolation remains entirely undeveloped; and since the soul is
entirely dependent on the bodily organs, along with which it originates,
grows, and declines, it is subject to mortality. Not only animals, as
Descartes has shown, but men, who differ from the brutes only in degree,
are mere machines; by the soul we mean that part of the body which thinks,
and the brain has fine muscles for thinking as the leg its coarse ones for
walking.

[Footnote 1: La Mettrie was born at St. Malo, and educated in Paris, and in
Leyden under Boerhave; he died in Berlin, whither Frederick the Great
had called him after he had been driven out of his native land and from
Holland. On La Mettrie cf. Lange, _History of Materialism_, vol. ii. pp.
49-91; and DuBois-Reymond's Address, 1875.]

If man is nothing but body, there is no other pleasure than that of the
body. There is a difference, however, between sensuous pleasure, which is
intense and brief, and intellectual pleasure, which is calm and lasting.
The educated man will prefer the latter, and find in it a higher and more
noble happiness; but nature has been just enough to grant the common
multitude, in the coarser pleasures, a more easily attainable happiness.
Enjoy the moment, t