Mind like water

This refers to the mental attitude while facing an actual opponent. It refers to the need of making the mind calm, like that of an undisturbed body of water. Smooth water reflects accurately the image of all objects within its range, and if the mind is kept calm, comprehension of the opponents movements, both psychological and physical, will be both immediate and accurate, and one's responses, both defensive and offensive, will be appropriate and
adequate.
On the other hand, if the surface of the water is disturbed, the images it reflects will be distorted. In other words, if the mind is preoccupied with thoughts of attack and defense it will not properly comprehend the opponent's intentions creating an opportunity for the opponent to attack. Water also other properties. Water can be quite destructive. In fact, over time, water is one of the most destructive forces on earth. Your mind must be like water. When necessary, be as destructive as you must.

Mind like the moon

This refers to the need to be constantly aware of the totality of the opponent and his/her movements, just as moonlight shines equally upon everything within its range. This means that one should watch just part of the opponents body such as the hands or feet, rather watch the entire body. With the thorough development of this attitude, the consciousness will be immediately aware of any openings in the opponent's defenses. Clouds blocking the light of the moon are likened to nervousness or distractions. These distractions stop the light from shining on everything. Likewise, they make comprehension of and reaction to the opponent's moves more difficult than they need to be

citation? author?

Koyama Sensei