Samyama — The Combined Practice of the Three Inner Limbs
Samyama (literally 'holding together') is the simultaneous, unified practice of Dharana, Dhyana, and Samadhi on a single object — the master key that unlocks direct knowledge of and mastery over any phenomenon.
Sutra 3.4 introduces Samyama: 'trayam ekatra samyamah' — the three (Dharana, Dhyana, Samadhi) practiced together on one object is Samyama. The third chapter of the Yoga Sutras then lists dozens of extraordinary powers (siddhis) that arise from Samyama on specific objects: Samyama on the sun gives knowledge of the solar system; Samyama on the moon gives knowledge of the arrangement of stars; Samyama on the relationship of ear and space gives supernatural hearing; Samyama on the heart gives knowledge of another's mind. Whatever Samyama is applied to becomes completely transparent to the meditator's consciousness. This is Patanjali's theory of knowledge: genuine knowing is not the application of conceptual frameworks to objects but the dissolution of the knower into the known.
The three practiced together on one object is Samyama.
Philosopher Michael Polanyi's concept of 'indwelling' — the mode of knowing in which the knower subsidiarily dwells within their tools and objects to understand them from the inside — is the closest Western philosophical parallel to Patanjali's Samyama as the union of knower and known.
Yoga Sutras of Patanjali