Sixthly, Names of simple Ideas not arbitrary, but perfectly taken from the existence of things.
Sixthly, The names of simple ideas, substances, and mixed modes have also this difference: that those of MIXED MODES stand for ideas perfectly arbitrary; those of SUBSTANCES are not perfectly so, but refer to a pattern, though with some latitude; and those of SIMPLE IDEAS are perfectly taken from the existence of things, and are not arbitrary at all.

Which, what difference it makes in the significations of their names, we shall see in the following chapters.
Simple modes.
The names of SIMPLE MODES differ little from those of simple ideas..