ly led to believe that things have always been as we
see them, and not as they have progressively been brought about.

"Among the changes which nature everywhere incessantly produces in
her _ensemble_, and her laws remain always the same, such of these
changes as, to bring about, do not need much more time than the
duration of human life, are easily understood by the man who
observes them; but he cannot perceive those which are accomplished
at the end of a considerable time.

"If the duration of human life only extended to the length of a
_second_, and if there existed one of our actual clocks mounted and
in movement, each individual of our species who should look at the
hour-hand of this clock would never see it change its place in the
course of his life, although this hand would really not be
stationary. The observations of thirty generations would never learn
anything very evident as to the displacement of this hand, because
its movement, only being that made during half a minute, would be
too slight to make an impression; and if observations much more
ancient should show that this same hand had really moved, those who
should see the statement would not believe it, and would suppose
there was some error, each one having always seen the hand on the
same point of the dial-plate.

"I leave to my readers all the applications to be made regarding
this supposition.

"_Nature_, that immense totality of different beings and bodies, in
every part of which exists an eternal circle of movements and
changes regulated by law; totality alone unchangeable, so long as it
pleases its SUBLIME AUTHOR to make it exist, should be regarded as a
whole constituted by its parts, for a purpose which its Author alone
knows, and not exclusively for any one of them.

"Each part necessarily is obliged to change, and to cease to be one
in order to constitute another, with interests opposed to those of
all; and if it has the power of reasoning it finds this whole
imperfect. In reality, however, this whole is perfect, and
completely fulfils the end for which it was designed."

The last work in which Lamarck discussed the theory of descent was in
his introduction to the _Animaux sans Vertebres_. But here the only
changes of importance are his four laws, which we translate, and a
somewhat different phylogeny of the animal kingdom.

The four laws differ from the two given in the