The man who has reached that level of existence where he can doubtlessly make a difference, usually has been separated from his lower nature. He became one with everything, a realized man.
The old Indian science of non-dualism is called Advaita Vedanta.
The Sanskrit word Vedanta means the end of knowledge and refers to transcendental knowledge not to what a man learns by head. This path of knowledge is a long journey of wisdom that can be achieved gradually and with big sincerity towards oneself.
This path needs a lot of self-discipline.
Insight is a child of knowledge.
Experience and knowledge become one.
Jnana yogi is anyone who has a clear insight into the world of all things, people, events.
All four Vedas, Rig Veda, Sam Veda, Yajur Veda and Artharvaveda are collections of texts that the Upanishads are part of and they talk about Jnana Yoga.