Müller shared these views of Rudolphi with regard to vivisection. The uncertainty of the conclusions, the amount of suffering inflicted, and the indefiniteness of the conditions of experiment, so that the conclusions could not have any very great weight, or any special accuracy of information, made him consider such experiments, unless very carefully conducted by trained investigators, as largely a waste of time and infliction of unnecessary pain and a leading astray of physiological advance because of the uncertainty involved. The qualities in Müller's "Hand-book of Physiology," which gave it its greatest value, are the thorough review of all of the physiological literature of the world which it contains, and the greatest number of original observations it details as the basis of the principles enunciated. Müller himself said, in the preface to his "Hand-book": "I need scarcely remark that it is the duty of a scholar to make himself acquainted with the progress of science among all nations; and this is now possible and, moreover, quite indispensable in these days of progress. A purely German, French, or English school of medical science is barbarism; and in Germany we would consider the idea of an isolated English or French system of natural history, physiology or medicine just as barbarous as the notion of Prussian, Bavarian, or Austrian medicine or physiology." How valuable the book was as the corner-stone of modern German medicine, may best be judged from Virchow's opinion of it. He says in his panegyric of Müller: