But suppose that this multitude of views or glimpses of an object proceeds not from experience, but from a voluntary act of the imagination; this effect does not follow, or at least, follows not in the same degree.

For though custom and education produce belief by such a repetition, as is not derived from experience, yet this requires a long tract of time, along with a very frequent and undesigned repetition.

In general we may pronounce, that a person who would voluntarily repeat any idea in his mind, though supported by one past experience, would be no more inclined to believe the existence of its object, than if he had contented himself with one survey of it.
Beside the effect of design; each act of the mind, being separate and independent, has a separate influence, and joins not its force with that of its fellows.

Not being united by any common object, producing them, they have no relation to each other; and consequently make no transition or union of forces.

This phaenomenon we shall understand better afterwards.
My second reflection is founded on those large probabilities, which the mind can judge of, and the minute differences it can observe betwixt them.