republic (books 1 - 5)   

only to provide the best for them, since the perfection of the art
is already insured whenever all the requirements of it are satis-
fied. And that was what I was saying just now about the ruler.
I conceived that the art of the ruler, considered as a ruler,
whether in a State or in private life, could only regard the good
of his flock or subjects; whereas you seem to think that the
rulers in States, that is to say, the true rulers, like being in
authority.

Think! Nay, I am sure of it.

Then why in the case of lesser offices do men never take them
willingly without payment, unless under the idea that they
govern for the advantage not of themselves but of others? Let
me ask you a question: Are not the several arts different, by
reason of their each having a separate function? And, my
dear illustrious friend, do say what you think, that we may
make a little progress.

Yes, that is the difference, he replied.

And each art gives us a particular good and not merely a
general one--medicine, for example, gives us health; naviga-
tion, safety at sea, and so on?

Yes, he said.

And the art of payment has the special function of giving
pay: but we do not confuse this with other arts, any more than
the art of the pilot is to be confused with the art of medicine,
because the health of the pilot may be improved by a sea voy-
age. You would not be inclined to say, would you? that navi-
gation is the art of medicine, at least if we are to adopt your
exact use of language?

Certainly not.

Or because a man is in good health when he receives pay
you would not say that the art of payment is medicine?

I should not.

Nor would you say that medicine is the art of receiving pay
because a man takes fees when he is engaged in healing?

Certainly not.

And we have admitted, I said, that the good of each art is
specially confined to the art?

Yes.

Then, if there be any good which all artists have in common,
that is to be attributed to something of which they all have the
common use?

True, he replied.

And when the artist is benefited by receiving pay the ad-
vantage is gained by an additional use of the art of pay, which
is not the art professed by him?

He gave a reluctant assent to this.