Both these kinds of passions pursue good, and avoid evil; and both of them are encreased or diminished by the encrease or diminution of the good or evil.

But herein lies the difference betwixt them: The same good, when near, will cause a violent passion, which, when remote, produces only a calm one.

As this subject belongs very properly to the present question concerning the will, we shall here examine it to the bottom, and shall consider some of those circumstances and situations of objects, which render a passion either calm or violent.
It is a remarkable property of human nature, that any emotion, which attends a passion, is easily converted into it, though in their natures they be originally different from, and even contrary to each other.
It is true; in order to make a perfect union among passions, there is always required a double relation of impressions and ideas; nor is one relation sufficient for that purpose.

But though this be confirmed by undoubted experience, we must understand it with its proper limitations, and must regard the double relation, as requisite only to make one passion produce another.

When two passions are already produced by their separate causes, and are both present in the mind, they readily mingle and unite, though they have but one relation, and sometimes without any.
The predominant passion swallows up the inferior, and converts it into itself.