Sophie's World is a novel written by Jostein Gaarder. The book follows the story of Sophie Amundsen, a girl who takes a course on philosophy by Alberto Knox.


Sophie receives two mysterious letters at her house, asking her "Who are you?" and "Where does the world come from?". The letter is addressed to Hilde Knag c/o Sophie. These questions make Sophie ponder about life, and thus she begins her long philosophical journey.

For the following weeks Sophie begins to receive letters about the history of philosophy anonymously. Soon, her correspondent reveals himself as Alberto Knox. Throughout her philosophy course, Sophie learns about the classic Greek philosophers such as Socrates and Plato, all the way to Karl Marx and Sigmund Freud.

Eventually, the narration switches to Hilde Knag. It is revealed that her father, Albert Knag, is an author who created Sophie and Alberto. Alberto and Sophie speed through a plethora of philosophers, and as the novel progresses Sophie begins to understand more of life and her world.

At a garden party near the end of the book, Albeto and Sophie disappear from the world after learning that they are a figment of Albert Knag's mind. Albert Knag is coming to visit Hilde, and Sophie and Alberto drive to meet Hilde at Lillesand. During Sophie and Alberto's journey, they realize they can go through everything and that no one can hear them; they are essentially spirits from books. They eventually meet Hilde and Albert, but they cannot interact with each other. However, Sophie manages to elicit a small response after hitting Hilde in the head with a wrench. Sophie thus begins learning how to interfere in the world of Hilde and Albert.


Throughout the story, Sophie learns about several different figures in philosophy. Following is a list of some:

Figure Description
Heraclitus/Parmenides Heraclitus: Everything is in a constant state flux. Change is the basic principle. The world is characterized by opposites.

Parmenides: Nothing can change; sensory perception is unreliable.

Empedocles Nothing changes. Basic elements: Earth, Fire, Water, Air. All matter is constituted by these.
Anaxagoras/Democritus Anaxogoras: All matter made of tiny particles called atoms.

Democritus: Came after Anaxagoras. Believed atoms were uncuttable, and there is an infinite amount of atoms.

Socrates "Gadfly of Athens". Questioned people about everything.
Plato Socrates's pupil.
  • Believed in Ideas - eternal and immutable. All objects have eternal form which real objects are based from. For example, there is the idea horse, a horse's perfect form. Basically, every horse in reality is based off the idea horse.
  • Reality divided into Senses and Ideas. Man made up of three parts: Head, source of reason; Chest, source of courage; Abdomen, source of appetite.
Aristotle Plato's pupil.
  • Natural scientist and biologist, created science to explain the world. Life consists of Plants and Animals
  • Logic and syllogisms, i.e. a conclusion based on two assumptions
  • Four causes: Final Cause, Material Cause, Efficient Cause, and Formal Cause. God is the Final Cause.
  • Innate reason. Ideas spring from senses and observations only.
  • Ethics: happiness. Golden Mean.
  • Politics: Democracy is best; Monarchy and aristocracy are not.
  • Zeno: Stoicism - each person is part of a community, or microcosm, of the world. Also believed human laws were flawed natural law imitations. Stoicism led to Humanism.
  • Diogenes: Cynicism - happiness is not derived from material goods. Stayed in a barrel and told king to move out of his way.
  • Epicurus: Epicureanism - highest good is pleasure.
  • Neoplatonism: Body and soul are polar opposites. The closer to god, the purer the soul.
  • Mysticism: Being one with god.
Thomas Aquinas God exists due to reason and faith. God is evidence of Final Cause - Christianized Aristotle.
Rene Descartes Rationalist, believed reason is the path to knowledge. Cogito ergo sum" ("I think therefore I am").
Baruch Spinoza Rejected Bible, thought it as product of humans in history. Jesus revolutionary, religions should value love. Laws of God governed humans. Rejected by Jews and Christians, and disowned by family.
John Locke Tabula rasa, blank slate. Man's mind starts clean, and experience creates the mind. Empiricist - those who believed mind consists of things observed by senses.
George Berkeley Since we exist in the mind of God, all thought has cause beyond experience under God. No other perspective for reality.
David Hume Daily experience forms basic ideas, accumulating into complex ideas. For example, basic ideas of human + wings = angels. We can conceive of things like angels, but not experience them. Impressions are experiences at the moment, and ideas are reflections of those impressions.
Immanuel Kant
  • Saw flaws and merits in both rationalism (knowledge from mind) and empiricism (knowledge from senses).
  • Senses affected by time and space. We only see what we perceive in our world, as it is conditioned. In other words, we see what the physical world looks like, not what it is. This is called Law of Causality. Therefore, we can never have definite knowledge of something, only knowledge on how they appear to us.
  • Material of knowledge is things we do not know until we perceive them. Form of knowledge is the thing perceived by man, governed by time and space and the Law of Cause and Effect.
  • Questions such as "Is man immortal?"; "Does God exist?"; and "Is the universe infinite?" are impossible to answer. This is because there is no sensory evidence for these, so we can't form knowledge, sense, and reason.
  • Regarding existence of God: neither reason nor senses prove anything; faith comes into play. Proposition that cannot be proved but occurs as moral necessity. Difference of right and wrong is matter of reason.
  • Moral laws are as universal as physical laws. Everyone acts the same, in general. Free will is a function of our own moral laws which we may choose to obey or disobey.
  • Categorical Imperative - evaluates motivation for our actions.
Hegel History is like rivers: There is one truth, but then another idea comes into conflict with this truth, and they merge into another truth. This is called thesis, antithesis, and synthesis. A thesis and antithesis lead to synthesis.

Believed all knowledge is human knowledge, no fixed, eternal truths. No truth above human reason.

Kierkegaard Existence defined by actions and action based on faith. One cannot know objectively that one must believe in faith.

Three stages in life: aesthetic, ethical, and religious stages. Aesthetic is living for enjoyment. This will lead to eventual angst and hopelessness, called existential situation. The person will have to make their own choice - moral or immoral - until they eventually reach the highest stage --the religious stage.

Friedrich Nietzsche Sought for revaluation of everything. Physical world only exists, ignore supernatural ideas. "God is dead".
Sartre Man must create values or else he will feel useless. Existence greater than actions, man is responsible for creating himself and being responsible for everything done. Individual creates meaning in meaningless world.
Karl Marx
  • Philosophy basis on action. Society based on material, economic, and social relations and also of religion, art, and philosophy.
  • In the modern world, there is conflict between proletariat and bourgeoisie (workers and middle class). Capitalists exploit worker by pocketing the profit from the worker. Worker rebels and forms classless society, called communism.
Charles Darwin Sailed on HMS Beagle to observe nature. Scientific works contradict Bible teachings on creation. Every species had been created separately, not from God. Evolution: species adapt and the strongest survive to this day.
Sigmund Freud Human psychology consists of id, ego, and superego. Id is the creative force that urges people to fulfill survival instincts and pleasure. Ego is the person's link to reality. Superego informs people of morally unacceptable behavior, and people repress these actions.

Theories on the unconscious. Man is always under attack from irrational impulses; humans always have to repress these urges to remain in society.