What is the origin of "mental imagery?"

The use of mental imagery goes back to our most ancient sources. Thousands of years ago we find a clear depiction of this process in the experience of the prophet Ezekiel, who travels in an inward imaginal journey to the throne of God. In fact, in biblical times there were schools called Sons of the Prophets in which these imaging techniques were taught. As time went on a tradition emerged called Chariot or Throne mysticism that became an important branch of western spiritual practice called Kabbalah, the word itself meaning "to receive." Eventually the Catholic Church took up these practices in the person of some well–known saints including: Hildegarde of Bingen, Ignatius of Loyola, Teresa of Avila, as main luminaries. At the time of the Renaissance, mental imagery was the major technique of medical practice for treating people with physical illness. The name of the technique associates with this direction was called "complexio."

In sum: mental imagery has a long, unabated, and distinguished history of which the above represents only a brief pinkie–nail sketch. In the twentieth century, mental imagery had begun to flourish more extensively in Europe and America, especially in the latter half. Such names as Robert Desoille (Directed Waking Dream), Hanscarl Leuner (Guided Affective Imagery), Carl Jung (Active Imagination), and most importantly, Mme. Colette Aboulker–Muscat (Waking Dream Therapy), stand out as seminal contributors. To this list I add my own as the American link of this great tradition.