Most people who study yoga eventually encounter a distinction that gets mentioned once and then passed over quickly. Some texts are Śruti. Others are Smṛti. The teacher says this matters and moves on. The student writes it down and forgets it. It matters more than almost anything else in the tradition. And the reason it gets passed over quickly is that explaining it properly requires sitting with a claim that the modern mind does not know what to do with.
Śruti was not written. It was received.
What the word means
Śruti comes from the Sanskrit root śru to hear. To hear something that was already there. To receive something that was already there. Not to compose. Not to reveal in the way a prophet receives a divine message. To hear something that was already there.
The Vedas: the four collections of Ṛg, Yajur, Sāma, and Atharva along with the Upaniṣads that emerge from them, carry the designation Śruti. They are apauruṣeya not of human authorship. No sage composed them. No deity dictated them. The ṛṣis who are associated with them are called dṛṣṭas (seers) or more precisely, receivers. They did not generate this knowledge. They received it.
For a Western reader, the immediate instinct is to reach for a familiar framework. Was this like Moses receiving the Ten Commandments? Was it vision, prophecy, divine inspiration? The answer is no to all of these. The Abrahamic idea of revelation involves a personal God communicating to a human recipient. Apauruṣeya means something fundamentally different. It means this knowledge does not belong to anyone. No individual owns it, authored it, or stands behind it as its source. It was there before the ṛṣis heard it and it remains there still.
A closer analogy, though still imperfect, is mathematics. When a mathematician discovers a theorem, we do not say they invented it. The relationship between prime numbers existed before anyone found it. The mathematician became the person whose mind was refined enough to perceive what was already operating. Apauruṣeya is something like this except applied not to physical laws but to the deepest laws of consciousness and reality.