No man is invincible, and therefore no man can fully understand that which would make him invincible. Even with complete and thorough study there is always the possibility of being defeated and although one may be expert in a particular form, mastery is something a man never stops seeking to attain.
Miyamoto MusashiEven if you strive diligently on your chosen path day after day, if your heart is not in accord with it, then even if you think you are on a good path, from the point of view of the straight and true, this is not a genuine path. If you do not pursue a genuine path to its consummation, then a little bit of crookedness in the mind will later turn into a major warp. Reflect on this.
Miyamoto Musashi