In preparing this volume for the press, knowing that it will now be subjected to the criticisms of a very numerous and intelligent body of my professional brethren, I have been anxious to render it worthy of their approbation as far as lay in my power. At the request of the Council I have made considerable omissions in my commentary as formerly printed, more especially in regard to modern authorities; it being thought advisable not to bring the annotations further down than the period of the Arabian writers. I have also made not a few additions and alterations which I hope will be considered as improvements. In performing this part of my task I have greatly profited by the aid and valuable criticisms of two esteemed friends, Sir William Hamilton of Edinburgh, and Dr. Greenhill of Oxford. I am sensible that it is to the growing conviction in the profession, of the value of the ancient authorities, that I owe the very flattering distinction which my work has now obtained; and I shall have great satisfaction in reverting to the labours of former years if they should now prove instrumental in increasing the desire of becoming acquainted with the views and practice of our forefathers. That the ancient literature of medicine has been too much neglected in this country is not disputed by any competent judge; and it would appear from the remarks of M. Hecker, in his address to the physicians of Germany, given in his admirable work on Epidemics,[1] that the profession on the Continent is not much in advance of us in this respect. [1] Dr. Babington’s Translation; Sydenham edition, p. xv. The time, however, it is to be hoped, is not far distant when the medical profession will everywhere be impressed with the importance of becoming properly acquainted with the views of the animal economy and of its derangements, entertained by three of the most intellectual nations of mankind; and when every newly-broached hypothesis will be tested by a comparison with doctrines of a similar nature advanced in former days, and every newly-proposed remedy will be subjected to a like ordeal. Surely every age ought to endeavour to benefit by the experiments, whether successful or otherwise, of all preceding ones; instead of every generation commencing a new series of trials, and wandering over the same ground in search of truths which had been long ago discovered; or in stumbling through the mazes of error without regarding the beacons set up by their forefathers to direct the footsteps of their descendants. If the wisdom of antiquity be entitled to high reverence in any case, it surely is so in medicine, founded as this art especially is on general observation and experience.