Nothing is more requisite for a true philosopher, than to restrain the intemperate desire of searching into causes, and having established any doctrine upon a sufficient number of experiments, rest contented with that, when he sees a farther examination would lead him into obscure and uncertain speculations.

In that case his enquiry would be much better employed in examining the effects than the causes of his principle.
Amongst the effects of this union or association of ideas, there are none more remarkable, than those complex ideas, which are the common subjects of our thoughts and reasoning, and generally arise from some principle of union among our simple ideas.

These complex ideas may be divided into Relations, Modes, and Substances.

We shall briefly examine each of these in order, and shall subjoin some considerations concerning our general and particular ideas, before we leave the present subject, which may be considered as the elements of this philosophy.
SECT.

V.OF RELATIONS.
The word RELATION is commonly used in two senses considerably different from each other.