make a division into parts which were also classes.

YOUNG SOCRATES: Very true; but I wish that this distinction between a part
and a class could still be made somewhat plainer.

STRANGER: O Socrates, best of men, you are imposing upon me a very
difficult task. We have already digressed further from our original
intention than we ought, and you would have us wander still further away.
But we must now return to our subject; and hereafter, when there is a
leisure hour, we will follow up the other track; at the same time, I wish
you to guard against imagining that you ever heard me declare--

YOUNG SOCRATES: What?

STRANGER: That a class and a part are distinct.

YOUNG SOCRATES: What did I hear, then?

STRANGER: That a class is necessarily a part, but there is no similar
necessity that a part should be a class; that is the view which I should
always wish you to attribute to me, Socrates.

YOUNG SOCRATES: So be it.

STRANGER: There is another thing which I should like to know.

YOUNG SOCRATES: What is it?

STRANGER: The point at which we digressed; for, if I am not mistaken, the
exact place was at the question, Where you would divide the management of