— 518 —
Ideas of the leading Qualities of Substances, are best got by shewing.
      §20. These leading sensible Qualities are those, which make the
chief Ingredients of our Specifick Ideas, and consequently the most
observable and unvariable part in the Definitions of our specifick
Names, as attributed to Sorts of Substances coming under our Know-
ledge. For though the Sound Man, in its own Nature, be as apt to
signifie a complex Idea made up of Animality and Rationality, united
— 519 —
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 as good a Definition of the Name Man, standing for that sort
or Creatures, will not be easy to shew: for ’tis 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 allow’d to be so, I do not know how they can be
excused from Murther, 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 it self to,
and inform no sort of Body, but one that is just of such an outward
Structure?
Locke Hum III, 11, §20, pp. 518-519