E. F. Schumacher in A Guide for the Perplexed:
Inner space is created by the [combined] powers of life, consciousness, and self-awareness; but we have direct and personal experience only of our own “inner space” and the freedom it affords us. The human …in his inner space …can develop a center of strength so that the power of freedom exceeds that of his necessity.
…We do not grasp that we are invisible. We do realize that we are in a world of invisible people. …We need not be surprised that most people throughout most of human history …have always claimed that we can learn to see the invisibility of the persons around us.