People who love books often accumulate large collections. And it can be frustrating when you find yourself wanting to consult or reread a particular one only to waste a lot of time tracking it down.

In an earlier post, I outlined the basics of using the Dewey Decimal Classification system for organizing your nonfiction books. If you have a lot of nonfiction print books in your collection, reading that post should be your first step.

If thirty or so of your books are philosophy or psychology read on for guidance on how to further subdivide these types of books.

100s     Philosophy and psychology

Philosophy books are books about how humans have answered deep, big picture questions like, “Where did we come from?” and “Why are we here?” Attempts to answer these questions across all time periods and cultures are in this section. Right in the middle of it are the psychology books that attempt to explain how the mind works using scientific models.

100-109   Philosophy, parapsychology, occultism, and psychology

This section is for works that discuss philosophy as a subject in itself. Any work that either contains several branches of philosophy or that answer broad philosophical questions belongs here. This includes books of theory, dictionaries, and encyclopedias, as well as research in philosophy and psychology. Philosophical histories and biographies round out this section.

Recommended books in general philosophy, parapsychology, occultism, and psychology:

• Philosophy: A Discovery in Comics by Margreet de Heer
• Dictionary of Untranslatables: A Philosophical Lexicon edited by Barbara Cassin
• The Philosophy Shop: Ideas, Activities, and Questions to Get People, Young and Old, Thinking Philosophically  edited by Peter Worley
• A History of Western Philosophy by Bertrand Russell
• The Pursuit of Wisdom: A Chronological Inquiry of the World’s Most Influential Seekers of Wisdom in the Fields of Theology, Philosophy, and Science by Dean Chavooshian

110-119     Metaphysics

Metaphysics refers to any reality beyond the perception of human sense organs. In other words, it is the study of anything and everything we cannot study through direct observation. We can speculate about these topics, but may never be able to know about them with objective certainty.

This includes ontology which is the study of being and existence. Cosmology books, which can cover aspects of the nature of the universe, such as cosmic harmony, space, time, change, structure, force and energy, as well as number and quantity, go in this section. All these are examined from a philosophical, not a scientific viewpoint, although the speculations contained in them are generally informed by science.

Recommended books in metaphysics:

• God’s Debris: A Thought Experiment by Scott Adams
• Cosmosophia: Cosmology, Mysticism, and the Birth of a New Myth by Theodore Richards
• The Image of Eternity: Roots of Time in the Physical World  by David Park

120-129     Epistemology, causation, humankind

Epistemology is the theory of knowledge. It attempts to answer questions like: “What does it mean to know something?” and  “What is the structure of knowledge?”

Causation asks questions such as, “What is the reason that things are as they are?”

Books on humankind would examine the nature of the soul and the mind. Comprehensive works on consciousness, philosophical anthropology, and the origin and destination of souls (as in reincarnation) would go here.

Recommended books in epistemology, causation, and humankind:

• Being Wrong: Adventures in the Margin of Error by Kathryn Schulz
• Causation: A User’s Guide by L.A. Paul and Ned Hall
• The Taming of Chance by Ian Hacking
• Consciousness Explained by Daniel Dennett
• The Denial of Death by Ernest Becker
• An End to Upside Down Thinking: Dispelling the Myth that the Brain Produces Consciousness, and the Implications for Everyday Life by Mark Gober
• The Conduct of Life  by Lewis Mumford
• The Meaning of Human Existence by Edward O. Wilson
• Surviving Death: A Journalist Investigates Evidence for Afterlife by Leslie Kean

130-139     Parapsychology and occultism

Many people are fascinated by parapsychology and occultism. Books on hauntings; divination, demonology, witchcraft, magic, spells, astrology, and works dealing with life after death are just a few topics shelved in this subcategory.

Recommended books in parapsychology and occultism:

• Parapsychology: A Handbook for the 21st Century edited by Etzel Cardean et al.
• Color Your Chakras: An Interactive Way to Understand the Energy Centers of the Body by Susan Shumsky
• Evidence of the Afterlife: The Science of Near-Death Experience by Jeffrey Long
• In the Devil’s Snare by Mary Beth Norton
• Holistic Tarot: An Integrative Approach to Using Tarot for Personal Growth by Benebell Wen
• The Forgotten Language: An Introduction to the Understanding of Dreams, Fairytales, and Myths by Erich Fromm
• The Mature Mind by H.A. Overstreet
• The Meaning of Persons by Paul Tournier

140-149     Specific philosophical schools and viewpoints

This is another section that covers a lot of ground, these books discuss the concepts of ideology, world views, systems of beliefs, critical appraisals and contain the collected writings of individual philosophers.

Recommended books in specific philosophical schools:

• At the Existentialist Cafe: Freedom, Being, and Apricot Cocktails with Jean-Paul Sartre, Simone de Beauvoir, Albert Camus, Martin Heidegger, Maurice Meleau-Ponty and Others by Sarah Bakewell
• American Transcendentalism: A History by Philip Gura
• Darwin’s Dangerous Idea by Daniel C. Dennett
• Mysticism: A Study of the Nature and Development of Man’s Spiritual Consciousness by Evelyn Underhill

150-159     Psychology

It’s hard to quickly summarize this massive division. It may seem strange that psychology is shoehorned into just one tens category surrounded on all sides by philosophy. But at the time Melvil Dewey created the system in the 1870s, psychology was still a budding science. In fact, the word psychology had not yet entered the common lexicon. Dewey labeled this category “Mental Faculties.” Freud hadn’t yet begun to publish his works.

This section contains general and comprehensive works of psychology which cover some or all the systems, viewpoints, groups of people, history, geographic treatments, and biographies involved with it. You would find the collected works or biographies of Sigmund Freud, Carl Jung, Alfred Adler, Howard Gardner, Steven Pinker, Susan Blackmore, and Daniel Kahneman here,  just to name a few.

The section also covers studies of sensory perceptions, emotions, and physiological drives. intelligence, memory, imagination, thought processes, will, motivation, and personality.

Applied psychology books are those that discuss counseling and self-help.

Recommended books in psychology:

• Positive Intelligence: Why Only 20% of Teams and Individuals Achieve Their True Potential, and How You Can Achieve Yours by Shirzad Chamine
• Freud: A Life for Our Times by Peter Gay
• Man’s Search for Himself by Rollo May
• What if This Were Enough? by Heather Havrilesky
• Influence: The Psychology of Persuasion by Robert B. Cialdini
• Thinking, Fast and Slow by Daniel Kahneman
• Islands of Genius: The Bountiful Mind of the Autistic, Acquired, and Sudden Savant by Darold A. Treffert
• Otherworlds: Psychedelics and Exceptional Human Experience by David Luke
• Quiet: The Power of Introverts in a World that Can’t Stop Talking by Susan Cain
• The Blank Slate by Steven Pinker
• Next of Kin: What Chimpanzees Have Taught Me About Who We Are by Roger Fouts and Stephen Tukel Mills
• Secrets from the Sofa: A Psychologist’s Guide to Achieving Personal Peace by Kenneth Herman

160-169     Philosophical logic

Logic is the science of reasoning and it involves logic operators and critical thinking. Books on inductive and deductive reasoning, fallacies, syllogisms, hypotheses, argument, and persuasion belong here.

Recommended books in logic:

• Guides to Straight Thinking by Stuart Chase
• If A then B: How the World Discovered Logic by Michael Shenefelt and Heidi White
• Surfaces and Essences: Analogy as the Fuel and Fire of Thinking by Douglas Hofstadter

170-179     Ethics

Books on morality, as it relates to conscience, social relations, work, and policies are shelved here.

A few other ethical topics are those involving environmental and ecological issues, the treatment of children and animals, respect for human life, capital punishment, euthanasia, abortion, and the ethics of violence and nonviolence.

Recommended books in ethics:

• A History of Western Morals by Crane Brinton
• The Ethical Project by Philip Kitcher
• Cosmopolitanism: Ethics in a World of Strangers by Kwame Anthony Appiah
• Galileo’s Middle Finger: Heretics, Activists, and the Search for Justice in Science by Alice Dreger
• The Seven Signs of Ethical Collapse: How to Spot Moral Meltdown in Companies–Before It’s Too Late by Marianne M. Jennings
• Whose View of Life? Embryos, Cloning, and Stem Cells by Jane Maienschein
• Lying: Moral Choice in Public and Private Life by Sissela Bok
• The CAFO Reader: The Tragedy of Industrial Animal Factories edited by Daniel Imhoff
• Wild Justice: The Evolution of Revenge by Susan Jacoby

180-189     Ancient, medieval, Eastern philosophy

Eastern philosophy refers to any philosophy originating in the Eastern Hemisphere, whether ancient, medieval, or modern, including those based on specific religions and from specific regions.

Ancient and medieval philosophies refer to those originating in the Western Hemisphere, such as pre-Socratic Greek philosophies, Sophistic, Socratic, and related Greek philosophies like Cynic and Elian philosophies. Platonic philosophies and Aristotelian philosophies, both ancient and modern also go here.

Recommended books in ancient, medieval, and Eastern philosophy:

• The Heart and Science of Yoga: The American Meditation Institute’s Empowering Self-Care Program for a Happy, Healthy, Joyful Life by Leonard Perlmutter
• Fragments of Parmenides: A Critical Text with Introduction, and Translation, The Ancient Testimonia and a Commentary by A. H. Coxon
• The Death of Socrates by Emily Wilson
• Plato at the Googleplex: Why Philosophy Won’t Go Away by Rebecca Goldstein

190-199     Modern Western and other non-Eastern philosophy

These include comprehensive works on modern philosophy and those relating to occupations (medicine, law, and education) and religious groups (Christian, Buddhist, and Islamic), as well as national and ethnic groups.

Recommended books in modern western philosophy:

• The Fragmentation of Being by Kristopher McDaniel
• Philosophical Explanations by Robert Nozick
• The Proper Study of Mankind: An Anthology of Essays by Isaiah Berlin
• Friedrich Nietzsche: A Philosophical Biography by Julian Young
• The Passion of Michel Foucault by James Miller
• Spinoza: A Life by Steven Nadler

Once you have further subdivided your philosophy and psychology books, be sure to update any spreadsheets or card catalogs you may have made for them. Part of the joy of having a system is that you will never need to worry about misplacing a beloved book again.

Are you a philosophy fan? Did anything about these subdivisions surprise you?