The constancy of our perceptions has the most considerable effect, and yet is attended with the greatest difficulties.

It is a gross illusion to suppose, that our resembling perceptions are numerically the same; and it is this illusion, which leads us into the opinion, that these perceptions are uninterrupted, and are still existent, even when they are not present to the senses.

This is the case with our popular system.

And as to our philosophical one, it is liable to the same difficulties; and is over-and-above loaded with this absurdity, that it at once denies and establishes the vulgar supposition.

Philosophers deny our resembling perceptions to be identically the same, and uninterrupted; and yet have so great a propensity to believe them such, that they arbitrarily invent a new set of perceptions, to which they attribute these qualities.