speech or reading the idea of, say, a Greek helmet, where no
direct use of any kind enters in. What shared activity is there
in learning from books about the discovery of America?

Since language tends to become the chief instrument of learning
about many things, let us see how it works. The baby begins of
course with mere sounds, noises, and tones having no meaning,
expressing, that is, no idea. Sounds are just one kind of
stimulus to direct response, some having a soothing effect,
others tending to make one jump, and so on. The sound h-a-t
would remain as meaningless as a sound in Choctaw, a seemingly
inarticulate grunt, if it were not uttered in connection with an
action which is participated in by a number of people. When the
mother is taking the infant out of doors, she says "hat" as she
puts something on the baby's head. Being taken out becomes an
interest to the child; mother and child not only go out with each
other physically, but both are concerned in the going out; they
enjoy it in common. By conjunction with the other factors in
activity the sound "hat" soon gets the same meaning for the child
that it has for the parent; it becomes a sign of the activity
into which it enters. The bare fact that language consists of
sounds which are mutually intelligible is enough of itself to
show that its meaning depends upon connection with a shared
experience.

In short, the sound h-a-t gains meaning in precisely the same way
that the thing "hat" gains it, by being used in a given way. And
they acquire the same meaning with the child which they have with
the adult because they are used in a common experience by both.
The guarantee for the same manner of use is found in the fact