“The wounds of the spirit heal and leave no scars.”
“Someone has inflicted the wounds and scars you now possess, but healing is left to you alone.”
1979
Related quotes

Les défauts de l'âme sont comme les blessures du corps: quelque soin qu'on prenne de les guérir, la cicatrice paraît toujours, et elles sont à tout moment en danger de se rouvrir.
Variant translation: The defects of the mind are like the wounds of the body. Whatever care we take to heal them the scars ever remain, and there is always danger of their reopening.
Maxim 194.
Reflections; or Sentences and Moral Maxims (1665–1678)

“Poetry heals the wounds inflicted by reason.”
As quoted in Quote, Unquote (1989) by Jonathan Williams, p. 136
“Even when the wound is healed, the scar remains.”
Maxim 236
Sentences, The Moral Sayings of Publius Syrus, a Roman Slave
Variant: Even when there is no law, there is conscience.

“Time may heal wounds, but it does not erase the scars.”
Source: Briar Rose (1992), Chapter 12 (p. 72)

Variant: The mind is a remarcable thing. Just because you can’t see the wound doesn’t mean it isn’t hurting
Source: The Pact

“The scar of fire, the dint of steel,
Are easier than Love's wounds to heal.”
Canto II
The Troubadour (1825)
Source: Translations, The Aeneid of Virgil (1866), Book I, p. 12