Memory and Imagination
Along with perception, memory and imagination name the main sensitive powers. Many of our memories are verbal and implement all the processes of thought, both perceptual and conceptual thought.
When our memories are not verbal, that which we remember recalls past events or occasions. The past, which no longer exists, becomes present to us in recollection. We actually have a nonexistent past present to us in our minds.
Imagination also presents to our minds objects that do not actually exist. It is the power by which we explore the realm of the possible. When our senses cooperate with our intellects and we are not conceptually blind, we can imagine objects which may exist at some future time, or which are merely figments or fictions of our imagination. They are intelligible to us, even though we understand them as constructed by us, such as mermaids and centaurs.
The intellectual imagination enriches human experience by giving us the power to deal with objects that are not accessible to other animals. The world in which animals live is limited to that which is perceptually present or remembered.
The characters in narrative fiction are our own imaginative constructs. Julius Caesar, for example, as described in Plutarch's Lives, can be remembered by us, but Julius Caesar, a character in a play by Shakespeare, is our own imaginative construct. It exists only in our imagination. It is a mental fiction.
Verbal memories do not persist for long periods. They are soon forgotten, though they can be revived. There is no purely intellectual memory. Instead the intellect forms habits. When we have the habit of understanding it retains what, at an earlier time, we understood. This habit of understanding is strengthened and reinforced by exercising the habit.
Adler's Philosophical Dictionary (1995)
Great Ideas from the Great Books (1963)
by Mortimer J. Adler