t to each other of the stimuli
received from the environment and responses directed upon it. Note that
the adjusting is reciprocal; the brain not only enables organic activity
to be brought to bear upon any object of the environment in response to
a sensory stimulation, but this response also determines what the next
stimulus will be. See what happens, for example, when a carpenter is
at work upon a board, or an etcher upon his plate--or in any case of a
consecutive activity. While each motor response is adjusted to the
state of affairs indicated through the sense organs, that motor response
shapes the next sensory stimulus. Generalizing this illustration, the
brain is the machinery for a constant reorganizing of activity so as to
maintain its continuity; that is to say, to make such modifications in
future action as are required because of what has already been done. The
continuity of the work of the carpenter distinguishes it from a routine
repetition of identically the same motion, and from a random
activity where there is nothing cumulative. What makes it continuous,
consecutive, or concentrated is that each earlier act prepares the way
for later acts, while these take account of or reckon with the results
already attained--the basis of all responsibility. No one who has
realized the full force of the facts of the connection of knowing with
the nervous system and of the nervous system with the readjusting of
activity continuously to meet new conditions, will doubt that knowing
has to do with reorganizing activity, instead of being something
isolated from all activity, complete on its own account.

(ii) The development of biology clinches this lesson, with its discovery
of evolution. For the philosophic significance of the doctrine of
evolution lies precisely in its emphasis upon continuity of simpler
and more complex organic forms until we reach man. The development of
organic forms begins with structures where the adjustment of environment
and organism is obvious, and where anything which can be called mind is
at a minimum. As activity becomes more complex, coordinating a greater
number of factors in space and time, intelligence plays a more and more
marked role, for it has a larger span of the future to forecast and plan
for. The effect upon the theory of knowing is to displace the notion
that it is the activity of a mere onlooker or spectator of the world,
the notion which goes with the idea of knowing as somethin