There are many ways of understanding simple things, but generally the opposite is true for difficult ideas

Do nothing which is of no use.

It is said the warrior's is the twofold Way of pen and sword, and he should have a taste for both Ways. Even if a man has no natural ability he can be a warrior by sticking assiduously to both divisions of the Way.

It is imperative to master the principles of the art of war and learn to be unmoved in mind even in the heat of the battle.

Do not regret what you have done

Aspire to be like Mt. Fuji, with such a broad and solid foundation that the strongest earthquake cannot move you, and so tall that the greatest enterprises of common men seem insignificant from your lofty perspective. With your mind as high as Mt Fuji you can see all things clearly. And you can see all the forces that shape events; not just the things happening near to you.

In battle, if you you make your opponent flinch, you have already won.