kind of initiative on the part of the larva, there is no sharp line of
demarcation between the instinct of the animal and the organizing work
of living matter. We may say, as we will, either that instinct organizes
the instruments it is about to use, or that the process of organization
is continued in the instinct that has to use the organ. The most
marvelous instincts of the insect do nothing but develop its special
structure into movements: indeed, where social life divides the labor
among different individuals, and thus allots them different instincts, a
corresponding difference of structure is observed: the polymorphism of
ants, bees, wasps and certain pseudoneuroptera is well known. Thus, if
we consider only those typical cases in which the complete triumph of
intelligence and of instinct is seen, we find this essential difference
between them: _instinct perfected is a faculty of using and even of
constructing organized instruments; intelligence perfected is the
faculty of making and using unorganized instruments_.

The advantages and drawbacks of these two modes of activity are obvious.
Instinct finds the appropriate instrument at hand: this instrument,
which makes and repairs itself, which presents, like all the works of
nature, an infinite complexity of detail combined with a marvelous
simplicity of function, does at once, when required, what it is called
upon to do, without difficulty and with a perfection that is often
wonderful. In return, it retains an almost invariable structure, since a
modification of it involves a modification of the species. Instinct is
therefore necessarily specialized, being nothing but the utilization of
a specific instrument for a specific object. The instrument constructed
intelligently, on the contrary, is an imperfect instrument. It costs an
effort. It is generally troublesome to handle. But, as it is made of
unorganized matter, it can take any form whatsoever, serve any purpose,
free the living being from every new difficulty that arises and bestow
on it an unlimited number of powers. Whilst it is inferior to the
natural instrument for the satisfaction of immediate wants, its
advantage over it is the greater, the less urgent the need. Above all,
it reacts on the nature of the being that constructs it; for in calling
on him to exercise a new function, it confers on him, so to speak, a
richer organization, being an artificial organ by which the natural
organism is extended. For eve