Samadhi — Absorption, When Meditator and Object Become One
Samadhi (absorption) is the eighth limb — the state in which the mind is so completely absorbed in the object of meditation that the meditator's sense of a separate self appears to dissolve, and only the object shines.
Sutra 3.3 completes the trio: 'tad evaartha maatra nirbhasam svarupa shunyam iva samadhih' — when the same (object) alone shines, as if empty of the form of the meditator, that is samadhi. The phrase 'svarupa shunyam iva' — 'as if empty of its own form' — is crucial: the meditator has not ceased to exist but has temporarily lost the sense of being a separate self observing an object. The experience is of pure object-awareness without a separate observer — which is why samadhi is described as a dissolution of subject-object duality. From the outside, samadhi may be indistinguishable from deep sleep. From the inside, it is the most vivid and real experience available to human consciousness.
When only the object shines, as if empty of the meditator's own form, that is samadhi.
Philosopher Thomas Nagel's question 'What is it like to be a bat?' — asking about subjective experience from a third-person perspective — is precisely the question that samadhi resolves experientially: in absorption, the distinction between the knower and the known temporarily collapses into pure knowing.
Yoga Sutras of Patanjali