5. Other men's ideas; real existence; and supposed real essences, are what men usually refer their ideas to.
First,
when the mind supposes any idea it has conformable to that in other men's minds, called by the same common
name; v.g. when the mind intends or judges its ideas of justice, temperance, religion, to be the same with what
other men give those names to.
Secondly, when the mind supposes any idea it has in itself to be conformable to some real existence. Thus the two
ideas of a man and a centaur, supposed to be the ideas of real substances, are the one true and the other false; the
one having a conformity to what has really existed, the other not.
Thirdly, when the mind refers any of its ideas to that real constitution and essence of anything, whereon all its
properties depend: and thus the greatest part, if not all our ideas of substances, are false.