It is a principle of the art of war that one should simply lay down his life and strike. If one's opponent also does the same, it is a even match. Defeating one's opponent is then a matter of faith and destiny.

To desire with one’s very soul every second of every day to accomplish one’s aim.

The deepest love is often hidden.

A samurai will use a toothpick even though he has not eaten. Inside the skin of a dog, outside the hide of a tiger.

One should make his decisions within the space of seven breaths.

The Four Oaths: Never be late with respect to the way of the warrior; be useful to the lord; be respectful to your parents; get beyond love and grief: exist for the good of man.

Having only wisdom and talent is the lowest tier of usefulness.