Samyama is a technical term in yoga and it means restraint. Samyama in yoga is applied to antaranga (the three inner aspects) of Patanjali’s eight-fold yoga, namely, dharana, dhyana and Samadhi. These three practices together form a continuum, and that is called samyama.
It is a complex process in which the state of dharana, after continued practice, gets converted into a state of dhyana, when, out of a multitude of experiences (pratyaya) about an object of concentration (desha), one single experience starts arising again and again, like a continuous flow, there being no other experience which intervenes. Such a state of dhyana is accompanied by awareness of one’s own existence. When that awareness fades away, dhyana gives away to Samadhi.
When an adept masters the state of samyama in respect of any object, he is advised by Patanjali to practice it further on finer and still finer objects (Yogasutra III 5 – 6).
Prolonged practice would make the intellect clear and pure by washing away impurities. Such an intellect becomes the abode of Viveka Khyati (self realization) that in the end leads to the state of nirbija (seedless) Samadhi.
Samyama on various objects yields siddhis (supernatural powers) involving knowledge of that object and even control of happenings and functions. These powers are described in detail by Patanjali. Thus, an adept can have knowledge of a previous life, of other minds, of the human body, and of the self. He can even disappear, fly in the air, have clairvoyance, clairaudience, and great physical powers. However, Patanjali does not encourage the attainment of siddhis.
Bibliography
Yoga Samyama (1975) Swami Gitananda – Satya Press Pondicherry
Encyclopedia of Hinduism Volume IX- page 162 - IHRF