Going up a mountain track, I fell to thinking.
Approach everything rationally, and you become harsh. Pole along in the stream of emotions, and you will be swept away by the current. Give free rein to your desires, and you become uncomfortably confined. It is not a very agreeable place to live, this world of ours. 
When the unpleasantness increases, you want to draw yourself up to some place where life is easier. It is just at the point when you first realize that life will be no more agreeable no matter what heights you may attain, that a poem may be given birth, or a picture created.

(Soseki Natsume, Alan Turney " THE THREE-CORNERED WORLD" ) 

故曰 知彼知己 百戰不殆
不知彼而知己 一勝一負
不知彼 不知己 毎戰必敗

Hense the saying: If you know the enemy and know yourself, you need not fear the result of a hundred battles.
If you know yourself but not the enemy, for every victory gained you will also suffer a defeat.
If you know neither, the enemy nor yourself, you will succumb in every battle.

(Sun Tzu, "The Art of War"- Attack by Stratagem)

出其所不趨 趨其所不意
行千里而不勞者 行於無人之地也
攻而必取者 攻其所不守也
守而必固者 守其所不攻也

Appear at points which the enemy must hasten to defend; march swiftly to places where you are not expected.
An army may march great distances without distress, if it marches through country where the enemy is not.
You can be sure of succeeding in your attacks if you only attack places which are undefended.
You can ensure the safety of your defense if you only hold positions that cannot be attacked.

(Sun Tzu, "The Art of War" - Weak Points and Strong )

色不異空 空不異色
色即是空 空即是色
受想行識 亦復如是
Form is emptiness; emptiness also is form.
Emptiness is no other than form; form is no other than emptiness.
In the same way, feeling, perception, formation, and consciousness are emptiness.

(The Heart Sutra)


Confucius said,
"If you learn without thinking, you cannot understand truly.
If you think without learning, you will be self-righteous."

(The Analects of Confucius)

Whoever has a desire to become great among you, let him be your servant
And whoever has a desire to be first among you, let him be servant of all.

(The Bible, Mark 10:43-44 )