The Greek science of medicine was one which reached a high degree of development. As early as the fifth century B.C. it appears in the school of Hippocrates, divested of nearly all trace of its origin in superstition and magic, and largely relying on careful observation and interpretation of symptoms. This school already possessed a considerable body of recorded observations. At Alexandria, later, further progress was made, especially in the subject of anatomy. At this time the dissection—and even vivisection—of the human body was practiced, though there are few traces of it earlier, and later it was forbidden. The last great land-mark in the history of ancient medicine is to be found in the works of Galen (second century A.D.) who summed up, extended, and interpreted the medical knowledge of preceding times. In medicine, however, as in Greek science generally, theoretical and philosophical elements often prevailed to the detriment of the pragmatical. Examples of this are to be seen in the theory of the four humors, first found in the Hippocratic writings; in the belief of the Methodist school, which held that disease consisted in the contraction and relaxation of the pores (πόροι); and in the doctrines of the Pneumatic school, which maintained that health and disease resulted from the influence of the universal soul (πνεῦμα). A reaction against this tendency is evidenced by the empirics, who professed to reject all general notions and to rely on experience alone. However, the increasing predominance of the theoretical is shown in the case of Galen, who secured his ascendency over succeeding ages by his extravagant theoretical system rather than by his really great practical knowledge.