A great object, therefore, succeeding a small one makes a great emotion succeed a small one.

Now a great emotion succeeding a small one becomes still greater, and rises beyond its ordinary proportion.

But as there is a certain degree of an emotion, which commonly attends every magnitude of an object; when the emotion encreases, we naturally imagine that the object has likewise encreased.

The effect conveys our view to its usual cause, a certain degree of emotion to a certain magnitude of the object; nor do we consider, that comparison may change the emotion without changing anything in the object.

Those who are acquainted with the metaphysical part of optics and know how we transfer the judgments and conclusions of the understanding to the senses, will easily conceive this whole operation.
But leaving this new discovery of an impression, that secretly attends every idea; we must at least allow of that principle, from whence the discovery arose, that objects appear greater or less by a comparison with others.