The Odic force is the name given in the mid-19th century to a hypothetical vital energy or life force by Baron Carl von Reichenbach. Von Reichenbach coined the name from that of the Norse god Odin in 1845.
As von Reichenbach was investigating the manner in which the human nervous system could be affected by various substances, he conceived the existence of a new force allied to electricity, magnetism, and heat, a force which he thought was radiated by most substances, and to the influence of which different persons are variously sensitive. He named this vitalist concept Odic force.
Believers in Odic force said that it is visible in total darkness as colored auras surrounding living things, crystals, and magnets, but that viewing it requires hours first spent in total darkness. They also said that it resembles the eastern concepts prana and qi. However, they regarded the Odic force not as associated with breath, but rather with biological electromagnetic fields.
Reichenbach stated that through experimentation possibly one third of the population could view the phenomenon. Colleagues who were medical doctors in England claimed to have witnessed it, and discussion on the subject matter continues into the present day, with some claiming to be able to see it on sunny days with clear skies.