"Our objection to the old school," says Professor Curtis, "has ever been, that they not only have no true principles to guide their practice, but they have adopted, fixed, and obstinately adhered to principles the very reverse of the true. They have resolved that, in disease, nature turns a somerset--reverses all her normal laws, and requires them to do the same. They have decreed that the best means and processes to cure the sick are those which will most speedily kill them when in health. In the face of all reason and common sense, they have adhered to this doctrine and practice for the last three centuries, and they have been constrained to confess that the destruction they have produced on human life and health has far exceeded all that has been effected by the sword, pestilence, and famine. Still they obstinately persevere. They say their science is progressive--improving; yet its progression consists in contriving new ways and means to take part of the life's blood, and poison all the balance. "Medicine, being based on the laws of nature, is in itself an exact science; and every process of the act should be directed by those laws. "Medicine is a demonstrative science, and all its processes should be based on fixed laws, and be governed by positive inductions. Then, and not till then, will it deserve to be ranked among the exact sciences, and contemplated as a liberal art. "Truth is stationary; it never progresses. What was true in principle in the days of Adam is so still. To talk of progress in principle is ridiculous. Neither does a given practice progress. That which was ever intrinsically good is so still. To talk, then, of the progress in principles of medicine is absurd. We may learn the truth or error of principles, and the comparative value or worthlessness of practices; but the principles are still the same. This is our progress in knowledge, not the progress of science or art. The constant changes that have taken place in the adoption and rejection of various principles and practices have ever been an injury to the healing art. Both truth and falsehood, separately and combined, have been alternately received and rejected; and this is that progress which is made in a circle, and not in lines direct. The fault of the cultivators of medicine has been, not that they never discovered the truth nor adopted the right practice, but that they adopted wrong principles and practices as often as the right, and rejected the right as readily as the wrong. They have ever been ready to prove many, if not all things; but to cast off the bad and hold fast to the good, they seem to have had but little discrimination and power. They say truly, that the object of the healing art is to aid nature in the prevention and cure of her diseases; yet, in practice, they do violence to nature in the use of the lancet and poison."