Thus these two eminent chemists, and too many of their followers, frequently imposed their writings upon the unguarded reader, and themselves upon the vulgar, for men of profound knowledge in the medical art, and as great adepts in chemistry: and being puffed up with the high opinion entertained of their new art, or new medicines, and their own great wisdom, they rejected the philosophical theory of medicine by Galen and Avicenna, then so much in vogue. They were right in doing this, and might have done great service to mankind, if they had not set up their own imaginary chemical theory in its place, which was neither founded upon observations, nature, nor reason, and had no existence but in their own vain imaginations. Thus they supposed a malignity which caused all diseases, as well inflammatory as other fevers, and which was to be forced out of the body by sweating, with their hot therapeutics; they, therefore, attacked all fevers with this chemical ammunition, and attempted to carry them with fire and storm, prescribing the praecipitatus diaphoreticus and sweating regimen, which must have been fatal to many, and no doubt would have been so to many more, if van Helmont had not allowed his patients to dilute the medicine with a thin diet, which rendered the calorific method less fatal. But, as the learned Dr. Friend judiciously remarks, if any did escape after that hot regimen, it was through a fiery trial. Thus the chemists, without any rational theory, or regard to nature, and what she indicated or did;--without duly considering how the morbid matter, which caused the disease, was to be concocted and fitted to be carried off by some critical evacuation; or how to assist nature to bring that crisis on, according to the Hippocratic method;--without considering the benefit of the rational, cooling, antiphlogistic practice of the Arabians--they introduced their sudorific regimen instead; and this regimen was soon after brought into use in England, and most other countries, where it continued to be the practice for many years afterwards, as may be seen by the authors of those times, until the judicious and honest Dr. Sydenham wisely rejected and exploded it, introducing the rational method of Hippocrates and the cooling regimen of the Arabians, which he seems rather to have taken _ex ipsa re et ratione_ from nature and reason, than from the works of the Arabian physicians, with which he appears not to have been acquainted, as he never mentions them.