Our habit is to divide up our human world into compartments of different sorts of ‘realities’: natural and artificial, physical and moral, organic and juridical, for instance.
In a space-time, legitimately and perforce extended to include the movements of the mind within us, the frontiers between these pairs of opposites tend to vanish. Is there after all such a great difference from the point of view of the expansion of life between a vertebrate either spreading its limbs or equipping them with feathers, and an aviator soaring on wings with which he has the ingenuity to provide himself?The Phenomenon of Man