And yet were you not saying, just now, that craftsmen might be temperate in
doing another's work, as well as in doing their own?

I was, he replied; but what is your drift?

I have no particular drift, but I wish that you would tell me whether a
physician who cures a patient may do good to himself and good to another
also?

I think that he may.

And he who does so does his duty?

Yes.

And does not he who does his duty act temperately or wisely?

Yes, he acts wisely.

But must the physician necessarily know when his treatment is likely to
prove beneficial, and when not? or must the craftsman necessarily know when
he is likely to be benefited, and when not to be benefited, by the work
which he is doing?

I suppose not.

Then, I said, he may sometimes do good or harm, and not know what he is
himself doing, and yet, in doing good, as you say, he has done temperately
or wisely. Was not that your statement?