Yet priests, says Baas, from the Brahman caste, and the sub-castes, the Vaisya and Vaidya, officiated for a long time as teachers of medicine and as physicians. The Vaidyas, as the higher of the two sub-castes, included the physicians proper; while the Vaisyas, or lower caste, furnished nurses.[238] When Buddhism passed into modern Hinduism (750-1000 A.D.) the rules of caste became stricter, and the old fetters were reimposed, and the Brahmans returned to their ancient principles which forbade them to contaminate themselves with blood or morbid matter; they withdrew from all practice of medicine, and left it entirely to the Vaidyas. After a time these also shrank from touching dead bodies. Then public hospitals were abolished when Buddhism fell. The Mohammedan conquests which began about 1000 A.D. introduced foreign practitioners of physic, who derived their knowledge from Arabic translations of Sanskrit medical classics and monopolised the patronage of the Mohammedan aristocracy.[239] The only remains of the Buddhist hospitals now existing are the various institutions for animals, supported principally by the Jains, a sort of Protestants against Brahmanism.[240] The Mohammedan medical practitioners were called “Hukeems,” who followed the principles of Arabian medicine derived from Greek sources. As a rule these practitioners only attended on nobles and chiefs. There is no evidence even that the Mohammedan invaders employed medical men for their armies.[241] Dr. Benjamin Heyne, in his _Tracts on India_, says,[242]— “The medical works of the Hindus are neither to be regarded as miraculous productions of wisdom, nor as repositories of nonsense. Their practical principles, as far as I can judge, are very similar to our own; and even their theories may be reconciled with ours, if we make allowance for their ignorance of anatomy, and the imperfections of their physiological speculations.” In surgery they attained to high proficiency, and our modern surgeons have even been able to borrow from them the operation of rhinoplasty.[243] Concerning the medicinal properties of minerals (stones and metals), plants, animal substances, and the chemical analysis and decomposition of these, we have also learned much that is extremely valuable from the Hindus. Their _Materia Medica_ is so important, and has played so large a part in Western medical science, that we cannot afford to despise it, though the Hindus have contributed so little to the study of natural science.[244] Veterinary medicine, so far as the diseases of horses and elephants are concerned, has received special attention from the Hindus.