That which is common to all (cf.

Lemma II., above), and which is equally in a part and in the whole, does not constitute the essence of any particular thing.
Proof .-- If this be denied, conceive, if possible, that it constitutes the essence of some particular thing; for instance, the essence of B.

Then (II.Def.

ii.) it cannot without B either exist or be conceived; but this is against our hypothesis.
Therefore it does not appertain to B's essence, nor does it constitute the essence of any particular thing.

Q.E.D.
PROP.XXXVIII.