Tao Te Ching – Lao Tzu – chapter 31
Good weapons are instruments of fear; all creatures hate them.
Therefore followers of the Tao never used them.
The wise man prefers the left.
The man of war prefers the right.
Weapons are instruments of fear; they are not a wise man’s tools.
He uses them only when he has no choice.
Peace and quiet are dear to his heart.
And victory no cause for rejoicing.
If you rejoice in victory, then you delight in killing;
If you delight in killing, you cannot fulfill yourself.
On happy occasions precedence is given to the left,
On sad occasions to the right.
In the army the general stands on the left,
The commander-in-chief on the right.
This means that war is conducted like a funeral.
When many people are being killed,
They should be mourned in heartfelt sorrow.
That is why a victory must be observed like a funeral.