re are we to attribute to this new
kind of being? We reply, that it is the receptacle, and in a manner the
nurse, of all generation. I have spoken the truth; but I must express
myself in clearer language, and this will be an arduous task for
many reasons, and in particular because I must first raise questions
concerning fire and the other elements, and determine what each of them
is; for to say, with any probability or certitude, which of them should
be called water rather than fire, and which should be called any of them
rather than all or some one of them, is a difficult matter. How, then,
shall we settle this point, and what questions about the elements may be
fairly raised?

In the first place, we see that what we just now called water, by
condensation, I suppose, becomes stone and earth; and this same element,
when melted and dispersed, passes into vapour and air. Air, again, when
inflamed, becomes fire; and again fire, when condensed and extinguished,
passes once more into the form of air; and once more, air, when
collected and condensed, produces cloud and mist; and from these, when
still more compressed, comes flowing water, and from water comes earth
and stones once more; and thus generation appears to be transmitted from
one to the other in a circle. Thus, then, as the several elements never
present themselves in the same form, how can any one have the assurance
to assert positively that any of them, whatever it may be, is one thing
rather than another? No one can. But much the safest plan is to speak of
them as follows:--Anything which we see to be continually changing, as,
for example, fire, we must not call 'this' or 'that,' but rather say
that it is 'of such a nature'; nor let us speak of water as 'this'; but
always as 'such'; nor must we imply that there is any stability in any
of those things which we indicate by the use of the words 'this' and
'that,' supposing ourselves to signify something thereby; for they
are too volatile to be detained in any such expressions as 'this,'
or 'that,' or 'relative to this,' or any other mode of speaking which
represents them as permanent. We ought not to apply 'this' to any of
them, but rather the word 'such'; which expresses the similar principle
circulating in each and all of them; for example, that should be called
'fire' which is of such a nature always, and so of everything that has
generation. That in which the elements severally grow up, and appear,
and decay, i