which the new science demanded?

It is at this point that Leibniz produces the speculative postulate of his
system. Why not reverse the relation, and make the members represent the
mind as the mind represents the members? For then the unity of person
represented in the mind will become something actual in the members also.

Representation appears to common sense to be a one-way sort of traffic. If
my mind represents my bodily members, something happens to my mind, for it
becomes a representation of such members in such a state; but nothing
happens to the members by their being so represented in the mind. The [22]
mental representation obeys the bodily facts; the bodily facts do not obey
the mental representation. It seems nonsense to say that my members obey my
mind _because_ they are mirrored in it. And yet my members do obey my mind,
or at least common sense supposes so. Sometimes my mind, instead of
representing the state my members are in, represents a state which it
intends that they shall be in, for example, that my hand should go through
the motion of writing these words. And my hand obeys; its action becomes
the moving diagram of my thought, my thought is represented or expressed in
the manual act. Here the relation of mind and members appears to be
reversed: instead of its representing them, they represent it. With this
representation it is the opposite of what it was with the other. By the
members' being represented in the mind, something happened to the mind, and
nothing to the members; by the mind's being represented in the members
something happens to the members and nothing to the mind.

Why should not we take this seriously? Why not allow that there is two-way
traffic--by one relation the mind represents the members, by another the
members represent the mind? But then again, how can we take it seriously?
For representation, in the required sense, is a mental act; brute matter
can represent nothing, only mind can represent. And the members are brute
matter. But are they? How do we know that? By brute matter we understand
extended lumps of stuff, interacting with one another mechanically, as do,
for example, two cogs in a piece of clockwork. But this is a large-scale
view. The cogs are themselves composed of interrelated parts and those
parts of others, and so on _ad infinitum_. Who knows what the ultimate
constituents really are? The 'modern' philosophers, certainly, have
proposed no hypothesis about the