Physics   

word 'is' they should be making the one to be many-as if 'one' and
'being' were always used in one and the same sense. What 'is' may be
many either in definition (for example 'to be white' is one thing, 'to
be musical' another, yet the same thing be both, so the one is many)
or by division, as the whole and its parts. On this point, indeed,
they were already getting into difficulties and admitted that the one
was many-as if there was any difficulty about the same thing being
both one and many, provided that these are not opposites; for 'one'
may mean either 'potentially one' or 'actually one'.
Part 3
If, then, we approach the thesis in this way it seems impossible for
all things to be one. Further, the arguments they use to prove their
position are not difficult to expose. For both of them reason
contentiously-I mean both Melissus and Parmenides. [Their premisses
are false and their conclusions do not follow. Or rather the argument
of Melissus is gross and palpable and offers no difficulty at all:
admit one ridiculous proposition and the rest follows-a simple enough
proceeding.] The fallacy of Melissus is obvious. For he supposes that
the assumption 'what has come into being always has a beginning'
justifies the assumption 'what has not come into being has no
beginning'. Then this also is absurd, that in every case there should
be a beginning of the thing-not of the time and not only in the case
of coming to be in the full sense but also in the case of coming to
have a quality-as if change never took place suddenly. Again, does it
follow that Being, if one, is motionless? Why should it not move, the
whole of it within itself, as parts of it do which are unities, e.g.
this water? Again, why is qualitative change impossible? But, further,
Being cannot be one in form, though it may be in what it is made of.
(Even some of the physicists hold it to be one in the latter way,
though not in the former.) Man obviously differs from horse in form,
and contraries from each other.
The same kind of argument holds good against Parmenides also, besides
any that may apply specially to his view: the answer to him being that
'this is not true' and 'that does not follow'. His assumption that one
is used in a single sense only is false, because it is used in
several. His conclusion does not follow, because if we take only white
things, and if 'white' has a single meaning, none the less what is
white will be many and not one. For what is white will not be one
either in the sense that it is continuous or in the sense that it must
be defined in only one way. 'Whiteness' will be different from 'what
has whiteness'. Nor does this mean that there is anything that can
exist separately, over and above what is white. For 'whiteness' and
'that which is white' differ in definition, not in the sense that they
are things which can exist apart from each other. But Parmenides had
not come in sight of this distinction.
It is necessary for him, then, to assume not only that 'being' has the
same meaning, of whatever it is predicated, but further that it means
(1) what just is and (2) what is just one.
It must be so, for (1) an attribute is predicated of some subject, so
that the subject to which 'being' is attributed will not be, as it is
something different from 'being'. Something, therefore, which is not
will be. Hence 'substance' will not be a predicate of anything else.
For the subject cannot be a being, unless 'being' means several
things, in such a way that each is something. But ex hypothesi 'being'
means only one thing.
If, then, 'substance' is not attributed to anything, but other things
are attributed to it, how does 'substance' mean what is rather than
what is not? For suppose that 'substance' is also 'white'. Since the
definition of the latter is different (for being cannot even be
attributed to white, as nothing is which is not 'substance'), it
follows that 'white' is not-being--and that not in the sense of a
particular not-being, but in the sense that it is not at all. Hence
'substance' is not; for it is true to say that it is white, which we
found to mean not-being. If to avoid this we say that even 'white'