How to Coach Yourself and Others Better Coaching Through Visualisation | Page 158

Socrates, is like a human being making mental images from the
sense data that he experiences.
More recently, Bishop George Berkeley has proposed similar ideas
in his theory of idealism. Berkeley stated that reality is equivalent to
mental images — our mental images are not a copy of another
material reality, but that reality itself. Berkeley, however, sharply
distinguished between the images that he considered to constitute the
external world, and the images of individual imagination. According
to Berkeley, only the latter are considered "mental imagery" in the
contemporary sense of the term.

David Deutsch addresses Johnson's objection to idealism in The
Fabric of &VƗG