Now,

20. Ideas of the leading Qualities of Substances are best got by
showing.

These leading sensible qualities are those which make the chief
ingredients of our specific ideas, and consequently the most observable
and invariable part in the definitions of our specific names, as
attributed to sorts of substances coming under our knowledge. For though
the sound MAN, in its own nature, be as apt to signify a complex idea
made up of animality and rationality, united in the same subject, as to
signify any other combination; yet, used as a mark to stand for a sort
of creatures we count of our own kind, perhaps the outward shape is as
necessary to be taken into our complex idea, signified by the word man,
as any other we find in it: and therefore, why Plato's ANIMAL IMPLUME
BIPES LATIS UNGUIBUS should not be a good definition of the name man,
standing for that sort of creatures, will not be easy to show: for it
is the shape, as the leading quality, that seems more to determine that
species, than a faculty of reasoning, which appears not at first, and in
some never. And if this be not allowed to be so, I do not know how they
can be excused from murder who kill monstrous births, (as we call them,)
because of an unordinary shape, without knowing whether they have a
rational soul or no; which can be no more discerned in a well-formed
than ill-shaped infant, as soon as born. And who is it has informed us
that a rational soul can inhabit no tenement, unless it has just such a
sort of frontispiece; or can join itself to, and inform no sort of body,
but one that is just of such an outward structure?

21. And can hardly be made known otherwise.

Now these leading qualities are best made known by showing, and can
hardly be made known otherwise. For the shape of a horse or cassowary
will be but rudely and imperfectly imprinted on the mind by words; the
sight of the animals doth it a thousand times better. And the idea of
the particular colour of gold is not to be got by any description of it,
but only by the frequent exercise of the eyes about as is evident in
those who are used to this metal, who frequently distinguish true from
counterfeit, pure from adulterate, by the sight, where others (who have
as good eyes, but yet by use have not got the precise nice idea of that
peculiar yellow) shall not perceive any difference. The like may be said
of those other simple ideas, peculiar in their kind to any substance;
for which prec