A brief history of monism

The intuition that everything is one is older than the word for it. Across millennia and continents, in temples and in laboratories, people keep arriving at the same suspicion: that beneath the countless separate things there is a single reality wearing many masks. Monism is the name philosophy gives that suspicion — from the Greek monos, one. The term is fairly recent, coined by the German philosopher Christian Wolff in the eighteenth century, but the idea it names is very old.

Ancient roots

The first Greek philosophers were already monists of a kind. Thales said everything was, at bottom, water; others named air or fire — one underlying substance beneath the many forms. Then Parmenides, in the fifth century BCE, pushed the thought to its edge: reality is one, whole, and unchanging, and the world of separate, shifting things is how it looks to the senses, not how it is. Centuries later the Neoplatonists, following Plotinus, described all things as flowing out of and returning to “the One,” a single source beyond being itself.

The East

Further east the intuition ran deeper and older still. In India, the Upanishads and then Advaita Vedanta — systematized by Adi Shankara around the eighth century CE — taught a-dvaita, “not two”: Brahman, the one reality, is all there is, the innermost self is that same reality, and the appearance of separateness is maya. In China, the Tao Te Ching pointed at the Tao, the one undivided way from which the ten thousand things arise. Similar currents run through Kashmir Shaivism, strands of Buddhist non-duality, and the Sufi teaching of wahdat al-wujud, the unity of being.

The modern West

The West’s great monist is Baruch Spinoza, who argued in the seventeenth century that there is only one substance — God, or Nature — and that minds and bodies and stars alike are modes of that single thing. The idea carried forward through Hegel’s one unfolding Absolute and Schopenhauer’s single Will beneath all appearances — the latter drawing openly on the Upanishads. By the turn of the twentieth century the biologist Ernst Haeckel had turned monism into an actual movement, a naturalistic view uniting mind and matter, while philosophers like William James and Bertrand Russell proposed a “neutral monism,” in which mind and matter are two aspects of one underlying stuff.

Science, and now

The old intuition keeps resurfacing in new vocabularies. It appears in physics’s search for one unified field, in ecology’s single biosphere, and in the study of consciousness, where the question of whether mind and matter are finally one thing remains stubbornly open. In the last century, writers such as Aldous Huxley and Alan Watts carried the non-dual traditions of the East into ordinary Western language, where they quietly reshaped how a great many people imagine the self.

Every age files the same discovery under a new name — substance, Brahman, the Tao, the One, the Absolute, the field. We are simply the latest to notice. Not two, the traditions kept saying. One, we would add.