THE REPUBLIC OF PLATO - Studyplace

38 CHAPTER IV [I. 352
is useful for certain kinds of work. Would you agree to define a
thing's function in general as the work for which that thing is the
only instrument or the best one
I don't understand.
Take an example. We can see only with the eyes, hear only
with the ears; and seeing and hearing might be called the functions
of those organs.
Yes.
Or again, you might cut vine-shoots with a carving-knife or a
chisel or many other tools, but with none so well as with a pruningknife
made for the purpose; and we may call that its function.
True.
Now, I expect, you see better what I meant by suggesting that
a thing's function is the work that it alone can do, or can do better
than anything else.
Yes, I will accept that definition.
Good, said I; and to take the same examples, the eye and the
ear, which we said have each its particular function: have they
not also a specific excellence or virtue Is not that always the case
with things that have some appointed work to do
Yes.
Now consider: is the eye likely to do its work well, if you take
away its peculiar virtue and substitute the corresponding defect
Of course not, if you mean substituting blindness for the power
of sight.
I mean whatever its virtue may be; I have not come to that yet.
I am only asking, whether it is true of things with a functioneyes
or ears or anything else-that there is always some specific virtue
which enables them to work well; and if they are deprived
of that virtue, they work badly.
I think that is true.
Then the next point is this. Has the soul a function that can be
performed by nothing else Take for example such actions as deliberating
or taking charge and exercising control: is not the soul
the only thing of which you can say that these are its proper and
peculiar work