n
the inert molecules of seed and soil these waves impinge, disturbing
the atomic equilibrium, which there is an immediate effort to restore.
The effort, incessantly defeated--for the waves continue to pour
in--is incessantly renewed; in the molecular struggle matter is
gathered from the soil and from the atmosphere, and built, in
obedience to the forces which guide the molecules, into the special
form of the tree. In a general way, therefore, the life of the tree
might be defined as an unceasing effort to restore a disturbed
equilibrium. In the building of crystals Nature makes her first
structural effort; we have here the earliest groping of the so-called
'vital force,' and the manifestations of this force in plants and
animals, though, as already stated, indefinitely more complex, are to
be regarded of the same mechanical quality as those concerned in the
building of the crystal.

Consider the cycle of operations by which the seed produces the plant,
the plant the flower, the flower again the seed, the causal line,
returning with the fidelity of a planetary orbit to its original point
of departure. Who or what planned this molecular rhythm? We do not
know--science fails even to inform us whether it was ever 'planned' at
all. Yonder butterfly has a spot of orange on its wing; and if we
look at a drawing made a century ago, of one of the ancestors of that
butterfly, we probably find the selfsame spot upon the wing. For a
century the molecules have described their cycles. Butterflies have
been begotten, have been born, and have died; still we find the
molecular architecture unchanged. Who or what determined this
persistency of recurrence? We do not know; but we stand within our
intellectual range when we say that there is probably nothing in that
wing which may not yet find its Newton to prove that the principles
involved in its construction are qualitatively the same as those
brought into play in the formation of the solar system. We may even
take a step further, and affirm that the brain of man--the organ of
his reason--without which he can neither think nor feel, is also an
assemblage of molecules, acting and reacting according to law. Here,
however, the methods pursued in mechanical science come to an end; and
if asked to deduce from the physical interaction of the brain
molecules the least of the phenomena of sensation or thought, I
acknowledge my helplessness. The association of both with the matter