1. Plato – Looking for Perfect FormsPlato said the world we touch is not the full story. He believed in “Forms,” perfect ideas that live in a higher place. A circle you draw is never perfect, but the “Form of Circle” is. In his famous Cave tale, people chained inside only see shadows and think those shadows are real. A wise person leaves the cave, sees the sun (truth), and must go back to help the others. Plato also planned a just city led by “philosopher-kings,” rulers who love wisdom more than power.2. Aristotle – Using Careful LogicPlato’s best student, Aristotle, liked to watch nature and sort facts. He made rules of logic so people could argue clearly—“A thing cannot be both cat and dog at the same time.” He drew maps of plants and animals, named the stars, and wrote about good habits. His “Golden Mean” says virtue sits between too much and too little: courage lies between rashness and fear.3. Francis Bacon – Trust the ExperimentJump many centuries to Francis Bacon in England. He was tired of empty talk. Bacon said, “Try things out—then you will know.” His new method of science starts with questions, gathers facts, and tests ideas. He dreamed this method would give people power over sickness and hunger.4. Baruch Spinoza – God Is in EverythingSpinoza lived in the Dutch city of Amsterdam. He said God and Nature are two names for the same great whole. Everything fits together like a giant puzzle. We feel free, but our choices rise from causes we do not see—like a wave moves because of the sea around it. Real freedom comes when mind understands those causes and learns to accept them.5. Voltaire – Shine a Light of ReasonVoltaire made fun of kings and priests who misused power. With quick wit he defended freedom of thought: “I disagree with what you say, but I will fight for your right to say it.” He loved simple human kindness, hated cruelty, and pushed for fair laws. Durant calls him a “fencer” whose sword was laughter.6. Immanuel Kant – Duty Above DesireKant worked alone in the small town of Königsberg. He said the mind does not just copy the world; it helps shape it with built-in rules of space, time, and cause. For morals, he gave the “Categorical Imperative”: act only in ways you wish everyone would act. Do right because it is right, not for reward.7. Arthur Schopenhauer – Life as Will and PainSchopenhauer felt the deepest force in us is blind “will,” always wanting, never resting. Want brings pain; getting what we want soon feels dull; then we want again. Escape comes through art, gentle love for all beings, and quiet mind (he admired Buddhism). His dark view later inspired many artists and thinkers.8. Herbert Spencer – Evolution EverywhereBefore Darwin became famous, Spencer spoke of “evolution.” He said the whole universe moves from simple to complex: stars, life, and even societies. In society he warned that too much help for the weak might slow progress, coining the phrase “survival of the fittest.” Durant points out this idea was often misused.9. Friedrich Nietzsche – Make Your Own ValuesNietzsche cried, “God is dead,” meaning old beliefs were fading. He urged people to create fresh values and become the “Overman,” a higher self who lives with courage and joy. His “will to power” is the drive to grow, to shape one’s life like art. He praised strength, music, and laughter over guilt and fear.10. Henri Bergson – The Flow of TimeBergson said clocks cut time into equal bits, but real time—“duration”—is a living flow, more like a song than a ruler. Life, he thought, shows a creative push called “élan vital” (life force). We can grasp this flow better with felt intuition than with dry math.