When you feel restless, sad, sorrowful and embittered, look for the cause, and if it is not worth being sorry about (and nothing that does not offend God is worth being sorry about), get rid of your anxiety; if you do not see the causes but feel restless and dissatisfied all the same, put up with it, arm yourself with patience, let the storm pass, and your inner peace will return.
This union, my sister, demands a heart at peace, calm, unalterable, like some place in heaven, and we can and must acquire it fighting hard whatever threatens if from outside ourselves.

Letter to Juana Gratia (1857)