Riches give satisfaction to their possessor; and this satisfaction is conveyed to the beholder by the imagination, which produces an idea resembling the original impression in force and vivacity.

This agreeable idea or impression is connected with love, which is an agreeable passion.

It proceeds from a thinking conscious being, which is the very object of love.

From this relation of impressions, and identity of ideas, the passion arises, according to my hypothesis.
The best method of reconciling us to this opinion is to take a general survey of the universe, and observe the force of sympathy through the whole animal creation, and the easy communication of sentiments from one thinking being to another.

In all creatures, that prey not upon others, and are not agitated with violent passions, there appears a remarkable desire of company, which associates them together, without any advantages they can ever propose to reap from their union.