considered that while heat and cold, moisture and dryness, succeeded one another throughout the year, the human body underwent certain analogous changes which influenced the diseases of the period. With regard to the second class of causes producing diseases, he attributed many disorders to a vicious system of diet, for excessive and defective diet he considered to be equally injurious.

In his medical doctrines Hippocrates starts with the axiom that the body is composed of the four elements -air, earth, fire, and water. From these the four fluids or humours (namely, blood, phlegm, yellow bile, and black bile) are formed. Health is the result of a right condition and proper proportion of these humours, disease being due to changes in their quality or distribuThus inflammation is regarded as the passing of blood into parts not previously containing it. In the course of a disorder proceeding favourably, these humours undergo spontaneous changes in quality. This process is spoken of as coction, and is the sign of returning health, as preparing the way for the expulsion of the morbid matters a state described as the crisis. These crises have a tendency to occur at certain periods, which are hence called critical days. As the critical days answer to the periods of the process of coction, they are to be watched with anxiety, and the actual condition of the patient at these times is to be compared with the state

which it was expected he ought to show. From these observations the physician may predict the course which the remainder of the disease will probably take, and derive suggestions as to the practice to be followed in order to assist Nature in her operations.

Hippocrates thus appears to have studied "the natural history of diseases." As stated above, his practice was to watch the manner in which the humours were undergoing their fermenting coction, the phenomena displayed in the critical days, and the aspect and nature of the critical discharges-not to attempt to check the process going on, but simply to assist the natural operation. His principles and practice were based on the theory of the existence of a restoring essence (or púois) penetrating through all creation; the agent which is constantly striving to preserve all things in their natural state, and to restore them when they are preternaturally deranged. In the management of this vis medicatrix naturæ the art of the physician consisted. Attention, therefore, to regimen and diet was the principal remedy Hippocrates employed; nevertheless he did not hesitate, when he considered that occasion required, to administer such a powerful drug as hellebore in large doses.

The writings which are extant under the name of Hippocrates cannot all be ascribed to him. Many were doubtless written by his family, his descendants, or his pupils. Others are productions of the Alexandrian

school, some of these being considered by critics as wilful forgeries, the high prices paid by the Ptolemies for books of reputation probably having acted as inducements to such fraud. The following works have generally been admitted as genuine :—

1. On Airs, Waters, and Places.

2. On Ancient Medicine.

3. On the Prognostics.

4. On the Treatment in Acute Diseases.

5. On Epidemics [Books I. and III.].

6. On Wounds of the Head.

7. On the Articulations.

8. On Fractures.

9. On the Instruments of Reduction. 10. The Aphorisms [Seven Books].

II. The Oath.

The works "On Fractures," "On the Articulations," 'On Injuries to the Head," and "On the Instruments of Reduction," deal with anatomical or surgical matters, and exhibit a remarkable knowledge of osteology and anatomy generally. It has sometimes been doubted if Hippocrates could ever have had opportunities of gaining this knowledge from dissections of the human body, for it has been thought that the feeling of the age was diametrically opposed to such a practice, and that Hippocrates would not have dared to violate this feeling. The language used, however, in some passages in the work.

"On the Articulations," seems to put the matter beyond doubt. Thus he says in one place, "But if one will strip the point of the shoulder of the fleshy parts, and where the muscle extends, and also lay bare the tendon that ⚫goes from the armpit and clavicle to the breast,” etc. And again, further on in the same treatise, "It is evident, then, that such a case could not be reduced either by succussion or by any other method, unless one were to cut open the patient, and then, having introduced the hand into one of the great cavities, were to push outwards from within, which one might do in the dead body, but not at all in the living."

His descriptions of the vertebræ, with all their processes and ligaments, as well as his account of the general characters of the internal viscera, would not have been as free from error as they are if he had derived all his knowledge from the dissection of the inferior animals. Moreover, it is indisputable that, within less than a hundred years from the death of Hippocrates, the human body was openly dissected in the schools of Alexandrianay, further, that even the vivisection of condemned criminals was not uncommon. It would be unreasonable to suppose that such a practice as the former sprang up suddenly under the Ptolemies, and it seems, therefore, highly probable that it was known and tolerated in the time of Hippocrates. It is not surprising, when we remember the rude appliances and methods which then

obtained, that in his knowledge of minute anatomy Hippocrates should compare unfavourably with anatomists of the present day. Of histology, and such other subjects as could not be brought within his direct personal observation, the knowledge of Hippocrates was necessarily defective. Thus he wrote of the tissues without distinguishing them; confusing arteries, veins, and nerves, and speaking of muscles vaguely as "flesh." But with matters within the reach of the Ancient Physician's own careful observation, the case is very different. This is well shown in his wonderful chapter on the clubfoot, in which he not only states correctly the true nature of the malformation, but gives some very sensible directions for rectifying the deformity in early life.

When human strength was not sufficient to restore a displaced limb, he skilfully availed himself of all the mechanical powers which were then known. He does not appear to have been acquainted with the use of pulleys for the purpose, but the axles which he describes as being attached to the bench which bears his name (Scamnum Hippocratis) must have been quite capable of exercising the force required.

The work called "The Aphorisms," which was probably written in the old age of Hippocrates, consists of more than four hundred short pithy sentences, setting forth the principles of medicine, physiology, and natural philosophy. A large number of these sentences are