republic (books 1 - 5)   

contains all these.

Then, again, there is the situation of the city--to find a place
where nothing need be imported is well-nigh impossible.

Impossible.

Then there must be another class of citizens who will bring
the required supply from another city?

There must.

But if the trader goes empty-handed, having nothing which
they require who would supply his need, he will come back
empty-handed.

That is certain.

And therefore what they produce at home must be not only
enough for themselves, but such both in quantity and quality
as to accommodate those from whom their wants are supplied.

Very true.

Then more husbandmen and more artisans will be required?

They will.

Not to mention the importers and exporters, who are called
merchants?

Yes.

Then we shall want merchants?

We shall.

And if merchandise is to be carried over the sea, skilful
sailors will also be needed, and in considerable numbers?

Yes, in considerable numbers.

Then, again, within the city, how will they exchange their
productions? To secure such an exchange was, as you will
remember, one of our principal objects when we formed them
into a society and constituted a State.

Clearly they will buy and sell.

Then they will need a market-place, and a money-token for
purposes of exchange.

Certainly.

Suppose now that a husbandman or an artisan brings some
production to market, and he comes at a time when there is no
one to exchange with him--is he to leave his calling and sit idle
in the market-place?

Not at all; he will find people there who, seeing the want,
undertake the office of salesmen. In well-ordered States they
are commonly those who are the weakest in bodily strength,
and therefore of little use for any other purpose; their duty is
to be in the market, and to give money in exchange for goods