Before we leave this subject, it may not be amiss to account for a pretty curious phaenomenon, viz, why we commonly keep at a distance such as we contemn, and allow not our inferiors to approach too near even in place and situation.  It has already been observed, that almost every kind of idea is attended with some emotion, even the ideas of number and extension, much more those of such objects as are esteemed of consequence in life, and fix our attention.  It is not with entire indifference we can survey either a rich man or a poor one, but must feel some faint touches at least, of respect in the former case, and of contempt in the latter.  These two passions are contrary to each other; but in order to make this contrariety be felt, the objects must be someway related; otherwise the affections are totally separate and distinct, and never encounter.  The relation takes place wherever the persons become contiguous; which is a general reason why we are uneasy at seeing such disproportioned objects, as a rich man and a poor one, a nobleman and a porter, in that situation.

This uneasiness, which is common to every spectator, must be more sensible to the superior; and that because the near approach of the inferior is regarded as .a piece of illbreeding, and shews that he is not sensible of the disproportion, and is no way affected by it.  A sense of superiority in another breeds in all men an inclination to keep themselves at a distance from him, and determines them to redouble the marks of respect and reverence, when they are obliged to approach him; and where they do not observe that conduct, it is a proof they are not sensible of his superiority.  From hence too it proceeds, that any great difference in the degrees of any quality is called a distance by a common metaphor, which, however trivial it may appear, is founded on natural principles of the imagination.  A great difference inclines us to produce a distance.  The ideas of distance and difference are, therefore, connected together.  Connected ideas are readily taken for each other; and this is in general the source of the metaphor, as we shall have occasion to observe afterwards.

SECT.  XI OF THE AMOROUS PASSION, OR LOVE BETWIXT THE SEXES

Of all the compound passions, which proceed from a mixture of love and hatred with other affections, no one better deserves our attention, than that love, which arises betwixt the sexes, as well on account of its force and violence, as those curious principles of philosophy, for which it affords us an uncontestable argument.  It is plain, that this affection, in its most natural state, is derived from the conjunction of three different impressions or passions, viz.  The pleasing sensation arising from beauty; the bodily appetite for generation; and a generous kindness or good-will.  The origin of kindness from beauty may be explained from the foregoing reasoning.  The question is how the bodily appetite is excited by it.