"Oses," said the coachman to Tom Brown, "as to wear blinkers, so's they see only wot's in front of 'em: and that's the safest plan for 'umble folk like you and me." Nature seems to have worked on much the same principle. Our sense organs and our brain operate as an intricate kind of filter which limits and directs the mind's clairvoyant powers, so that under normal conditions attention is concentrated on just those objects or situations that are of biological importance for the survival of the organism and the species. . . . As a rule, it would seem, the mind rejects ideas coming from another mind as the body rejects grafts coming from another body.

Sir Cyril Burt