"From the number of books written on philosophy, religion, arts and sciences, it might seem that if thoughts are things, and books the representatives of thoughts, the world of thought must be crowded. However, the world of thought is traveled by human thought on a small portion, and which borders on the psychic and physical worlds. There are highways and beaten roads as well as the paths where here and there some independent thinker has made a trail between the beaten roads, which, as he continued, became more distinct and extended, and as he completed his system of thought the trail became a road and could be traveled at any time by himself and other thinkers. The schools of thought we know of represent these highways and paths in the world of thought."