Everyone will readily allow that there is a considerable difference between the perceptions of the mind, when a man feels the pain of excessive heat, or the pleasure of moderate warmth, and when he afterwards recalls to his memory this sensation, or anticipates it by his imagination. These faculties may mimic or copy the perceptions of the senses; but they never can entirely reach the force and vivacity of the original sentiment…The most lively thought is still inferior to the dullest sensation. —Marcel proust
We like to think of memories as though they could restore to us things we've known in the past. But memories can't really bring things back; they only reproduce some fragments of our former states of mind, when various sights, sounds, touches, smells, and tastes affected us.
Then what makes some recollections seem so real? The secret is that real-time experience is just as indirect! The closest we can come to apprehending the world, in any case, is through the descriptions our agents make. In fact, if we inquired instead about why real things seem real, we would see that this depends, as well, on memories of things we've already known.
For instance, when you see a telephone, you have a sense not only of the aspects you can see — its color, texture, size, and shape — but also of how it feels to hold the instrument to your ear. You also seem to know at once what telephones are for: that you speak into here and listen there; that when it rings you answer it; that when you want to call, you dial it. You have a sense of what it weighs, of whether it is soft or hard, of what its other side is like — although you haven't even touched it yet. These apprehensions come from memories.
The Immanence Illusion: Whenever you can answer a question without a noticeable delay, it seems as though that answer were already active in your mind.
This is part of why we feel that what we see is present in the here and now. But it isn't really true that whenever a real object appears before our eyes, its full description is instantly available. Our sense of momentary mental time is flawed; our vision-agencies begin arousing memories before their own work is fully done. For example, when you see a horse, a preliminary recognition of its general shape may lead some vision-agents to start evoking memories about horses before the other vision-agents have discerned its head or tail. Perceptions can evoke our memories so quickly that we can't distinguish what we've seen from what we've been led to recollect.
This explains some of the subjective difference between seeing and remembering. If you first imagined a black telephone, you probably would not find it hard to reimagine it as red. But when you see a black telephone and then attempt to think of it as red, your vision-systems swiftly change it back! So the experience of seeing things has a relatively rigid character, in contrast to the experience of imagining things. Every change that the rest of your mind tries to impose upon your vision-agencies is resisted and usually reversed. Perhaps it is this descriptive rigidity that we identify with vividness or objectivity. I do not mean to suggest that this is usually an illusion, because it often truly reflects the persistency and permanence of actual physical objects. Sometimes, though, our sense of objectivity can get reversed — as when an attitude or memory becomes more stable and persistent than what it represents. For example, our attitudes toward things we love or loathe are often much less changeable than those things themselves — particularly in the case of other people's personalities. In instances like these, our private memories can be more rigid than reality.