Imagination is the production of sensations, feelings and thoughts informing oneself. These experiences can be re-creations of past experiences, such as vivid memories with imagined changes, or completely invented and possibly fantastic scenes. Imagination helps apply knowledge to solve problems and is fundamental to integrating experience and the learning process. As a way of building theory, it is called "disciplined imagination". A way of training imagination is by listening to storytelling (narrative), in which the exactness of the chosen words is how it can "evoke worlds".
Olin Levi Warner, Imagination (1896). Library of Congress Thomas Jefferson Building, Washington, D.C.
In their most common sense, the terms thought and thinking refer to conscious cognitive processes that can happen independently of sensory stimulation. Their most paradigmatic forms are judging, reasoning, concept formation, problem solving, and deliberation. But other mental processes, like considering an idea, memory, or imagination, are also often included. These processes can happen internally independent of the sensory organs, unlike perception. But when understood in the widest sense, any mental event may be understood as a form of thinking, including perception and unconscious mental processes. In a slightly different sense, the term thought refers not to the mental processes themselves but to mental states or systems of ideas brought about by these processes.
The Thinker by Rodin (1840–1917), in the garden of the Musée Rodin
Man thinking on a train journey