This poison was first discovered in 1788. It acts powerfully on the liver, causing jaundice and weight loss. The homeopathic remedy, which was proved in 1868, is used to treat severe mental fatigue and degenerative conditions of the spinal cord. The remedy's key use is for severe mental fatigue after prolonged mental strain, where indifference and a lack of willpower develop with an inability to undertake new things or to talk or think clearly. This condition, which may cause a burning, numb sensation along the spine, is common among students who have been studying constantly for exams. There is a general sense of heaviness in all parts of the body. There may be associated headaches and boils in the external ear. The severe mental fatigue may also be brought on by grief.