What does this quote mean?

“It was the best of times, it was the worst of times.”

Opposing conditions can exist at the same time, making an era or a life impossible to reduce to a single description.

Source note: A Tale of Two Cities, opening sentence.

“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.”

“All that glisters is not gold.”

Appearance can imitate value without possessing it, so the line encourages evidence and discernment before admiration or trust.

Source note: Act 2, Scene 7; the inscription warns against judging by outward appearance.

“The unexamined life is not worth living.”

Socrates links a worthwhile human life with reflection on beliefs, conduct, and reasons rather than unexamined routine.

Source note: Apology 38a; wording varies by translation.

“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.

“He who binds to himself a joy does the winged life destroy.”

Trying to possess a joyful moment permanently can damage it, while accepting impermanence allows experience to remain alive and free.

Source note: Short poem commonly titled “Eternity”; Blake contrasts grasping with the passing movement of joy.