What does this quote mean?

“The happiness of your life depends upon the quality of your thoughts.”

The line emphasizes the role of habitual judgment in shaping lived experience, a recurring theme in Stoic practice.

Source note: Common English rendering of a passage in Meditations; wording varies by translation.

“To define is to limit.”

Definitions clarify ideas but can also narrow them, especially when a label is treated as the complete reality of a person or experience.

Source note: The Picture of Dorian Gray, 1891 edition, Chapter 17; Lord Henry answers the Duchess of Monmouth’s question “What are you?” with “To define is to limit.”

“The universe is wider than our views of it.”

Reality exceeds any one viewpoint, so confidence in a perspective should leave room for what has not yet been seen.

Source note: Walden, Conclusion; Thoreau uses the sentence while arguing that familiar human views do not exhaust reality.

“A foolish consistency is the hobgoblin of little minds.”

Emerson attacks rigid consistency when it prevents people from revising judgment in the light of new thought.

Source note: Essay “Self-Reliance”; Emerson criticizes rigid adherence to past opinions when fresh judgment requires revision.

“There is nothing either good or bad, but thinking makes it so.”

The line separates events from the judgments people place on them, a useful distinction for thinking about perception and response.

Source note: Hamlet, Act 2, Scene 2; Hamlet says this to Rosencrantz and Guildenstern while explaining that Denmark feels like a prison to him. The line is dramatic dialogue, not a detached psychological proposition by Shakespeare.

“It is a narrow mind which cannot look at a subject from various points of view.”

Intellectual flexibility requires seeing how the same issue can appear from more than one position before settling on a judgment.

Source note: Middlemarch; the narrator contrasts narrow judgment with considering a subject from several points of view.