Spotted this passage on the train home today in Jung’s Symbols of Transformation (p 232):

The archetypes are the numinous structural elements of the psyche and possess a certain autonomy and specific energy which enables them to attract, out of the conscious mind, those contents which are best suited to themselves. The symbols act as transformers, their function being to convert libido from “lower” into “higher” form. This function is so important that feeling accords it the highest values. The symbol works by suggestion; that is to say, it carries conviction and at the same time expresses the content of that conviction. It is able to do this because of the numen, the specific energy stored up in the archetype. Experience of the archetype is not only impressive, it seizes and possesses the whole personality, and is naturally productive of faith.