Aphthous stomatitis of the mouth. The word is derived from the Greek word "aphtha" meaning "eruption" or "ulcer". The lesions of several other oral conditions are sometimes described as aphthae, including Bednar's aphthae (infected, traumatic ulcers on the hard palate in infants), oral candidiasis, and foot-and-mouth disease. When used without qualification, "aphthae" commonly refers to lesions of recurrent aphthous stomatitis. Since the word aphtha is often taken to be synonymous with ulcer, it has been suggested that the term "aphthous ulcer" is redundant, but it remains in common use. Stomatitis is also a non-specific term referring to any inflammatory process in the
The Canon of Medicine anatomy, and physiology. The book explains the causes of health and disease. Avicenna believed that the human body cannot be restored to health unless the causes of both health and disease are determined. He defined medicine ("tibb") as follows: Avicenna begins part one by dividing theoretical medicine and medical practice. He describes what he says are the "four causes" of illness, based on Aristotelian philosophy: The material cause, the efficient cause, the formal cause, and the final cause: Avicenna's thesis on the elements of the cosmos is described by Gruner as "the foundation of the whole "Canon"". Avicenna insists here