Description of density and fullness by Vladimir Vasiliev

Density is formed by our conscious mind, and it is a manifestation of fear.
An unconscious person has no density in his body; he is collapsed. When a strike comes from behind and you do not see it, no density is formed to protect you from it. Before a muscle is activated, fear in our consciousness creates density in this part of the body. Although not visible with the usual vision, it has a substance to it and can be sensed. It precedes the physical changes by a split second. Consciousness is primary and physical changes are secondary; both acting in the mechanism to protect your body.

A good way to understand 'fullness' is to look at a green apple and at a ripe one. When it is ripe, you see and sense that it is correct, balanced, and contains the force of life in it. When the body is 'full', it contains the physical power, the energy, and the clean thought in the right balance. We intuitively know that a green apple is not convincing and that a 'full' arm sure is.