As each soul transmigrates and reemerges into the stream of illusion, the ocean of infinite consciousness out of which it emerges is forgotten. It is as if there is a wall between the experience base of the embodied consciousness, what we call life, and the disembodied consciousness, what we call death.
The yogi awakens to this situation and becomes aware of the endless wheel of transmigration. The inability to operate consciously on both sides of the membrane separating life and death finally becomes an issue for them. They seek to pass through this membrane and remain conscious, once and for all merging the two poles of the inherent nature of the human being: individual identity and universal identity.
Samadhi, to put it simply, is the conscious passing through the membrane between life and death. This is the final aim of the entire science of yoga and meditation;the conscious merging of individual identity with the infinite.