(Latin: imago, image)
The faculty of representing to oneself objects not present, characters not existing in real life, conjunctions of events or circumstances never actually witnessed.
This faculty takes the impressions by external objects made on eye, ear, and other senses at one time or other, and presents them in the form of an image to the intellect.
It may present them just as they occur to the memory, or it may alter them, combine several together, and even create entirely new images.
These may be the result of voluntary and deliberate recollection, as of scenes of the past, or they may spring up spontaneously as in moments of reverie or the familiar day-dream.
The imagination exercises a motive force on the intellect and will.
It may be a power for evil and for good.
It may present a forbidden thing so vividly and alluringly as to excite passion, darken the intellect, and captivate the will.
On the other hand, it is a force in meditation helping to focus attention on the person, place, or event, chosen as the subject of meditation.
It is the starting point of all our intellectual and moral operations.
The intellect depends on it, but should always control it.
Unfortunately most people live more by imagination than by intellect; hence the misconceptions, misjudgments, prejudices, and even fears, or phobias, particularly in matters of religion.
The new psychology, so called, or the study of the soul which ignores the soul's existence, is largely to blame for this, since it stops at the imagination, or consideration of images, and never rises to the study of intellect and ideas.
New Catholic Dictionary