If an accident happen to a stage coach by which a passenger’s leg is broken, or his human form divine is otherwise injured, the coachman has no authority to bind his master by a contract with a surgeon to attend to the injury; nor if a lamp-lighter, by neglect, burn any person, has he, or any officers of the gas company, power to bind the company by a contract for the cure of the injured person [89]. If ordinary employees had such authority, then every servant who, by his negligence or misconduct, had caused injury to an individual, would have an implied authority to employ, on behalf and at the expense of his employer, any person he thought fit to remedy the mischief. |42| CHAPTER IV. WHO MAY PRACTISE. The law has nothing to do with the merits of particular systems or schools of medicine. Their relative merits may become the subject of inquiry when the skill or ability of a practitioner, in any given case, is to be passed upon as a matter of fact. But the law does not and cannot supply any positive rules for the interpretation of medical science. It is not one of those certain or exact sciences in which truths become established and fixed, but it is essentially progressive in its nature. No one system of practice has been uniformly followed, but physicians, from the days of Hippocrates, have been divided into opposing sects and schools. The sects of the dogmatists and the empirics divided the ancient world for centuries until the rise of the methodics, who in their turn gave way to innumerable sects. Theories of practice believed to be infallible in one age have been utterly rejected in another. For thirteen centuries Europe yielded to the authority of Galen. He was implicitly followed, his practice strictly pursued. Everything that seemed to conflict with his precepts was rejected; and yet, in the revolutions of medical opinion, the works of this undoubtedly great man were publicly burned by Paracelsus and his disciples; and for centuries following the medical world was divided between the Galenists and the chemists, until a complete ascendancy over both was obtained by the vitalists. This state of things has been occasioned by the circumstance that medical practitioners have often been more given to the formation of theories upon the nature of |43| disease and the mode of its treatment, than to that careful observation and patient accumulation of facts by which, in other sciences, the phenomena of nature have been unravelled. * * * It is not to be overlooked that as an art it has been characterised in a greater degree by fluctuations of opinion as to its principles and the mode of its practice than perhaps any other pursuit. That it has been distinguished by the constant promulgation and explosion of theories. That it has alternated between the advancement of new doctrines and the revival of old ones; and that its professors in every age have been noted for the tenacity with which they have clung to opinions, and the unanimity