The tantric sages say that prana shakti, or pranic energy, flows through the body in a network of pranic currents called nadis. The nadis are not physical structures, but rather are defined and delineated by the flow of prana in the same way an electromagnetic field is defined by the flow of electric current. This field of pranic flow constitutes the pranic body. The physical body is suspended in the pranic field, which penetrates, nourishes, and protects both the body and the mind, just as the atmosphere nourishes life on earth and the earth’s electromagnetic field protects it from harmful radiation. When prana withdraws from the body, the pranic field collapses, and we die. When we use prana wisely, we live fully and well.