time Jenner began his important work on the subject of vaccination; and the second to the present time. No attempt will be made in the following account to cover this second period.
The Beginnings of Medicine.—In the early period of man's existence upon this earth he must have possessed an exceedingly small stock of knowledge with regard to the maintenance of his body in health and with regard to the means which he should adopt in order to restore it to a normal condition after it had been injured by violence or impaired in its working machinery by disease. With the progress of time, utilizing his powers of observation and his reasoning faculty, he slowly made additions to his stock of facts of this nature. Thus, for example, he gradually learned that cold, under certain circumstances, is competent to produce pain in the chest, shortness of breath, active secretion of mucus, etc., and his instinct led him, when he became affected in this manner, to crave the local application of heat as a means of affording relief from these distressing symptoms. Again, when he used certain plants as food he could scarcely fail to note the facts that some of them produced a refreshing or cooling effect, that others induced a sensation of warmth, and finally that others still, by reason of their poisonous properties, did actual harm. Sooner or later, such phenomena as nausea, vomiting and diarrhoea would also be attributed by him to their true causes. In due course of time his friends and neighbors, having made similar observations and having tried various remedial procedures for the relief of their bodily ills, would come together and compare with him their several experiences; and so eventually the fact would be brought out that the particular method adopted by one of their number for the relief of certain symptoms had proved more effective than any of the others. Thus gradually this isolated community or tribe of men must have learned how to treat, more or less successfully, the simpler ills to which they were liable.
Lucien Le Clerc quotes from the Arab historian Ebn Abi Ossaïbiah the following account of the manner in which
