Disease is an abnormal state of the body which primarily and independently produces a disturbance in the normal functions of the body. It may be an abnormality of temperament or form (structure). Symptom is a manifestation of some abnormal state in the body. It may be harmful as a colic pain or harmless as the flushing of cheeks in peripneumonia.
AvicennaNow it is established in the sciences that no knowledge is acquired save through the study of its causes and beginnings, if it has had causes and beginnings; nor completed except by knowledge of its accidents and accompanying essentials.
Avicenna