Tao Te Ching, English by J.J.L. Duyvendak

31

Truly, it is because arms are instruments of evil, which for ever are loathed by all beings, that one who has the Way has no concern with them.
At home a nobleman values the left as the place of honour, but when he bears arms, he values the right as the place of honour.
Arms are instruments of evil and not the instruments proper to a nobleman. Only when forced to do so he bears them, and peace and quiet he sets above all. Even when he conquers, he finds no beauty in it. Should he find beauty in it, he would take pleasure in the slaughter of men. He who takes pleasure in the slaughter of men, will never get his will in All-under-heaven.
On joyful occasions the left is valued as the place of honour; on sad occasions the right is valued. The second-in-command is posted on the left, the commander-in-chief is posted on the right, which means that they are placed in accordance with the mourning rites. The slaughter of multitude of men is bewailed with sorrow and lamentation. Therefore, upon a victory in war, they are placed in accordance with the mourning rites.