distinguished each from each by one and the same method of
division. Thus the 'winged' species is simultaneous with the
'terrestrial' and the 'water' species. These are distinguished
within the same genus, and are opposed each to each, for the
genus 'animal' has the 'winged', the 'terrestrial', and the
'water' species, and no one of these is prior or posterior to
another; on the contrary, all such things appear to be
'simultaneous' in nature. Each of these also, the terrestrial,
the winged, and the water species, can be divided again into
subspecies. Those species, then, also will be 'simultaneous'
point of nature, which, belonging to the same genus, are
distinguished each from each by one and the same method of
differentiation.

But genera are prior to species, for the sequence of their being
cannot be reversed. If there is the species 'water-animal', there
will be the genus 'animal', but granted the being of the genus
'animal', it does not follow necessarily that there will be the
species 'water-animal'.

Those things, therefore, are said to be 'simultaneous' in nature,
the being of each of which involves that of the other, while at
the same time neither is in any way the cause of the other's
being; those species, also, which are distinguished each from
each and opposed within the same genus. Those things, moreover,
are 'simultaneous' in the unqualified sense of the word which
come into being at the same time.

Part 14