This is an attempt to combine two previous essays: “The Unfinished Road to Knowledge”, which presents the windmill model of cognitive development from childhood to mature science, also called the mandala of the sciences, and “The Realm of the Mind”, which describes the mental world as a darkened room with a central light of consciousness, and doors to the deep unconscious, to the body, to the collective unconscious, and to the spiritual.

In the first essay, cognitive development is traced through the Piaget stages to commonsense physics to Newtonian physics, representing the shaft of the windmill, and then branching out in four directions: (1) special relativity theory for the very fast and general relativity theory for the very large; (2) quantum theory for the very small; (3) thermodynamics and statistical mechanics for the very numerous; and (4) complexity theory (including networks, chaos, fractals etc.) for the very interactive.

The head of the windmill can be seen as relativity theory going to the left, quantum theory to the right, thermodynamics downward, and complexity theory upward. Then the horizontal (left-right) direction represents physical theories that are time-reversible, and the vertical (up and down) direction represents physical theories that have an arrow of time.

It is now proposed to add a fifth direction (perhaps going forward), which would be an exploration of the inner mental world. Since the mental world is itself not simple, as shown in the second essay treated here, we would need to explore not only the central room with its shaft of light, but also the separate side doors. The picture then might be: add another forward-going shaft to the original windmill, which then branches out to the head of a second windmill.