y be expected from a thing,
and the changes in things and persons which an activity may be expected
to produce. In other words, what he learns are connections. Even such
qualities as red color, sound of a high pitch, have to be discriminated
and identified on the basis of the activities they call forth and the
consequences these activities effect. We learn what things are hard and
what are soft by finding out through active experimentation what they
respectively will do and what can be done and what cannot be done with
them. In like fashion, children learn about persons by finding out what
responsive activities these persons exact and what these persons will
do in reply to the children's activities. And the combination of what
things do to us (not in impressing qualities on a passive mind) in
modifying our actions, furthering some of them and resisting and
checking others, and what we can do to them in producing new changes
constitutes experience. The methods of science by which the revolution
in our knowledge of the world dating from the seventeenth century, was
brought about, teach the same lesson. For these methods are nothing but
experimentation carried out under conditions of deliberate control. To
the Greek, it seemed absurd that such an activity as, say, the cobbler
punching holes in leather, or using wax and needle and thread, could
give an adequate knowledge of the world. It seemed almost axiomatic
that for true knowledge we must have recourse to concepts coming from a
reason above experience. But the introduction of the experimental method
signified precisely that such operations, carried on under conditions
of control, are just the ways in which fruitful ideas about nature are
obtained and tested. In other words, it is only needed to conduct such
an operation as the pouring of an acid on a metal for the purpose of
getting knowledge instead of for the purpose of getting a trade result,
in order to lay hold of the principle upon which the science of nature
was henceforth to depend. Sense perceptions were indeed indispensable,
but there was less reliance upon sense perceptions in their natural or
customary form than in the older science. They were no longer regarded
as containing within themselves some "form" or "species" of universal
kind in a disguised mask of sense which could be stripped off by
rational thought. On the contrary, the first thing was to alter and
extend the data of sense perception: to act upon