David Hume on the nature of belief, and especially on a comparison of belief with imagination:
"Belief is nothing but a more vivid, lively, forcible, firm, steady conception of an object, than what the imagination alone is never able to attain."
I disagree. And I disagree on Jamesian authority, drawing on The Principles of Psychology.
The problem is that Hume presumes belief is more than imagination -- it is imagination with more liveliness, force, etc. But a better understanding is that imagination is the more, not a more lively but a more complicated state of mind. It is the holding together of a conception AND a reason to doubt or deny that conception.
I imagine a unicorn in my barn. Or I believe there is a unicorn in the barn. On a Jamesian reading of this pair of possibilities, I conceive of the unicorn in the barn in either case, but in the imaginative case that conception is accompanied by my understanding of the mythical character of the beast.
Belief is that same conception without the second negating part. It is a minus, not a plus, to the imagination.