Quantities consist either of parts which bear a relative position
each to each, or of parts which do not. The parts of a line bear
a relative position to each other, for each lies somewhere, and
it would be possible to distinguish each, and to state the
position of each on the plane and to explain to what sort of part
among the rest each was contiguous. Similarly the parts of a
plane have position, for it could similarly be stated what was
the position of each and what sort of parts were contiguous. The
same is true with regard to the solid and to space. But it would
be impossible to show that the arts of a number had a relative
position each to each, or a particular position, or to state what
parts were contiguous. Nor could this be done in the case of
time, for none of the parts of time has an abiding existence, and
that which does not abide can hardly have position. It would be
better to say that such parts had a relative order, in virtue of
one being prior to another. Similarly with number: in counting,
'one' is prior to 'two', and 'two' to 'three', and thus the parts
of number may be said to possess a relative order, though it
would be impossible to discover any distinct position for each.
This holds good also in the case of speech. None of its parts has
an abiding existence: when once a syllable is pronounced, it is
not possible to retain it, so that, naturally, as the parts do
not abide, they cannot have position. Thus, some quantities
consist of parts which have position, and some of those which
have not.

Strictly speaking, only the things which I have mentioned belong
to the category of quantity: everything else that is called
quantitative is a quantity in a secondary sense. It is because we
have in mind some one of these quantities, properly so called,