What does this quote mean?

“It is in thy power whenever thou shalt choose to retire into thyself.”

A person can create an inward pause even when external conditions are noisy, using reflection to restore order before returning to action.

Source note: Meditations, Book IV, in George Long’s translation; this is the central clause of the retreat passage.

“Keep thy heart with all diligence; for out of it are the issues of life.”

Guarding inner life is presented as practical because attention and motives influence conduct downstream.

Source note: Proverbs 4:23 in the King James Version.

“Do no violence to yourself, respect in yourself the oscillations of feeling.”

Self-respect here means refusing to force inner life into an artificial uniformity; changing feelings can be observed and treated with patience instead of self-aggression.

Source note: Amiel's Journal, entry dated April 28, 1852, in Mary Augusta Ward’s public-domain translation; Amiel counsels patience with the movement of feeling.

“The mind is its own place.”

The statement emphasizes how mental framing can alter the experience of circumstances, for good or ill.

Source note: Paradise Lost, Book I; the fuller sentence continues with heaven and hell as states the mind can make.

“Look within. Within is the fountain of good, and it will ever bubble up, if thou wilt ever dig.”

Moral resources are pictured as something cultivated inwardly through continued examination rather than obtained only from external approval or circumstance.

Source note: Meditations, Book VII, section 59, George Long translation in Thoughts of Marcus Aurelius Antoninus.

“Otherwise, a man is the slave of what other people are pleased to think.”

Dependence on approval can turn other people’s judgments into a form of control; self-respect requires allowing outside opinion to inform rather than govern one’s sense of worth.

Source note: The Wisdom of Life; the sentence appears in Schopenhauer’s criticism of giving excessive weight to reputation and social opinion.