y's position in this matter I would recommend the reading of the 〃De Motu Cordis〃 itself； then the various passages relating to the circulation from Aristotle to Vesalius。 Many of these can be found in the admirable works of Dalton； Flourens； Richet and Curtis。＇31＇ In my Harveian Oration for 1906＇32＇ I have dealt specially with the reception of the new views； and have shown how long it was before the reverence for Galen allowed of their acceptance。 The University of Paris opposed the circulation of the blood for more than half a century after the appearance of the 〃De Motu Cordis。〃
＇30＇ De Plantis； Lib I； cap。 2。
＇*＇ Cesalpinus has also a definite statement of the circlewise process。Ed。
＇31＇ J。 C。 Dalton Doctrines of the Circulation； Philadelphia； 1884； Flourens Histoire de la decouverte de la circulation du sang； 2d ed。； Paris； 1857； Charles Richet Harvey； la circulation du sang； Paris； 1879； John G。 Curtis Harvey's views on the use of Circulation； etc。； New York； 1916。
＇32＇ Osler An Alabama Student and Other Biographical Essays； Oxford； 1908； p。 295。
To summarizeuntil the seventeenth century there were believed to be two closed systems in the circulation； （1） the natural； containing venous blood； had its origin in the liver from which； as from a fountain； the blood continually ebbed and flowed for the nourishment of the body； （2） the vital； containing another blood and the spirits； ebbed and flowed from the heart； distributing heat and life to all parts。 Like a bellows the lungs fanned and cooled this vital blood。 Here and there we find glimmering conceptions of a communication between these systems； but practically all teachers believed that the only one of importance was through small pores in the wall separating the two sides of the heart。 Observationmerely looking at and thinking about thingshad done all that was possible； and further progress had to await the introduction of a new method； viz。； experiment。 Galen； it is true； had used this means to show that the arteries of the body contained blood and not air。 The day had come when men were no longer content with accurate description and with finely spun theories and dreams。 It was reserved for the immortal Harvey to put into practice the experimental method by which he demonstrated conclusively that the blood moved in a circle。 The 〃De Motu Cordis〃 marks the final break of the modern spirit with the old traditions。 It took long for men to realize the value of this 〃inventum mirabile〃 used so effectively by the Alexandriansby Galenindeed； its full value has only been appreciated within the past century。 Let me quote a paragraph from my Harveian Oration。＇33＇ 〃To the age of the hearer； in which men had heard and heard only； had succeeded the age of the eye in which men had seen and had been content only to see。 But at last came the age of the hand the thinking； devising； planning hand； the hand as an instrument of the mind； now re…introduced into the world in a modest little monograph from which we may date the beginning of experimental medicine。〃
＇33＇ Osler： An Alabama Student； etc。； pp。 329…330。
Harvey caught the experimental spirit in Italy； with brain； eye and hand as his only aids； but now an era opened in which medicine was to derive an enormous impetus from the discovery of instruments of precision。 〃The new period in the development of the natural sciences； which reached its height in the work of such men as Galileo； Gilbert and Kepler； is chiefly characterized by the invention of very important instruments for aiding and intensifying the perceptions of the senses； by means of which was gained a much deeper insight into the phenomena than had hitherto been possible。 Such instruments as the earlier ages possessed were little more than primitive hand…made tools。 Now we find a considerable number of scientifically made instruments deliberately planned for purposes of special research； and as it were； on the threshold of the period stand two of the most important； the compound microscope and the telescope。 The former was invented about 1590 and the latter about 1608。〃＇34＇ It was a fellow professor of the great genius Galileo who attempted to put into practice the experimental science of his friend。 With Sanctorius began the studies of temperature； respiration and the physics of the circulation。 The memory of this great investigator has not been helped by the English edition of his 〃De Statica Medicina；〃 not his best work； with a frontispiece showing the author in his dietetic balance。 Full justice has been done to him by Dr。 Weir Mitchell in an address as president of the Congress of Physicians and Surgeons； 1891。＇35＇ Sanctorius worked with a pulsilogue devised for him by Galileo； with which he made observations on the pulse。 He is said to have been the first to put in use the clinical thermometer。 His experiments on insensible perspiration mark him as one of the first modern physiologists。
＇34＇ Dannemann： Die Naturwissenschaften in ihrer Entwickelung。。。； Vol。 II； p。 7； Leipzig； 1911。
＇35＇ See Transactions Congress Physicians and Surgeons； 1891； New Haven； 1892； II； 159…181。
But neither Sanctorius nor Harvey had the immediate influence upon their contemporaries which the novel and stimulating character of their work justified。 Harvey's great contemporary； Bacon； although he lost his life in making a cold storage experiment； did not really appreciate the enormous importance of experimental science。 He looked very coldly upon Harvey's work。 It was a philosopher of another kidney； Rene Descartes； who did more than anyone else to help men to realize the value of the better way which Harvey had pointed out。 That the beginning of wisdom was in doubt； not in authority； was a novel doctrine in the world； but Descartes was no armchair philosopher； and his strong advocacy and practice of experimentation had a profound influence in directing men to 〃la nouvelle methode。〃 He brought the human body； the earthly machine； as he calls it； into the sphere of mechanics and physics； and he wrote the first text…book of physiology； 〃De l'Homme。〃 Locke； too； became the spokesman of the new questioning spirit； and before the close of the seventeenth century； experimental research became all the mode。 Richard Lower； Hooke and Hales were probably more influenced by Descartes than by Harvey； and they made notable contributions to experimental physiology in England。 Borelli； author of the famous work on 〃The Motion of Animals〃 （Rome； 1680…1681）； brought to the study of the action of muscles a profound knowledge of physics and mathematics and really founded the mechanical； or iatromechanical school。 The literature and the language of medicine became that of physics and mechanics： wheels and pulleys； wedges； levers； screws； cords； canals。 cisterns； sieves and strainers； with angles； cylinders； celerity； percussion and resistance； were among the words that now came into use in medical literature。 Withington quotes a good example in a description by Pitcairne； the Scot who was professor of medicine at Leyden at the end of the seventeenth century。 〃Life is the circulation of the blood。 Health is its free and painless circulation。 Disease is an abnormal motion of the blood； either general or local。 Like the English school generally； he is far more exclusively mechanical than are the Italians； and will hear nothing of ferments or acids； even in digestion。 This； he declares； is a purely mechanical process due to heat and pressure； the wonderful effects of which may be seen in Papin's recently invented 'digester。' That the stomach is fully able to comminute the food may be proved by the following calculation。 Borelli estimates the power of the flexors of the thumb at 3720 pounds； their average weight being 122 grains。 Now； the average weight of the stomach is eight ounces； therefore it can develop a force of 117；088 pounds； and this may be further assisted by the diaphragm and abdominal muscles the power of which； estimated in the same way； equals 461；219 pounds！ Well may Pitcairne add that this force is not inferior to that of any millstone。〃＇36＇ Paracelsus gave an extraordinary stimulus to the study of chemistry and more than anyone else he put the old alchemy on modern lines。 I have already quoted his sane remark that its chief service is in seeking remedies。 But there is another side to this question。 If； as seems fairly certain； the Basil Valentine whose writings were supposed to have inspired Paracelsus was a hoax and his works were made up in great part from the writings of Paracelsus； then to our medical Luther； and not to the mythical Benedictine monk； must be attributed a great revival in the search for the Philosopher's Stone； for the Elixir of Life； for a universal medicine； for the perpetuum mobile and for an aurum potabile。＇37＇ I reproduce； almost at random； a page from the fifth and last part of the last will and testament of Basil Valentine （London； 1657）； from which you may judge the chemical spirit of the time。
＇36＇ Withington： Medical History from the Earliest Times； London； 1891； Scientific Press； p。 317。
＇37＇ See Professor Stillman on the Basil Valentine hoax； Popular Science Monthly； New York； 1919； LXXXI； 591…600。
Out of the mystic doctrines of Paracelsus arose the famous 〃Brothers of the Rosy Cross。〃 〃The brotherhood was possessed of the deepest knowledge and science； the transmutation of metals； the perpetuum mobile and the universal medicine were among their secrets； they were free from sickness and suffering during their lifetime； though subject finally to death。〃＇38＇
＇38＇ Ferguson： Bibliotheca Chemica； Vol。 II； p。 290。 For an account of Fludd and the English Rosicrucians see Craven's Life of Fludd； Kirkwall； 1902。
A school of a more rational kind followed directly upon the work of Paracelsus； in which the first man of any importance was Van Helmont。 The Paracelsian Archeus was the presiding spirit in living creatures； and worked through special local ferments； by which the functions of the organs are controlled。 Disease of any part represents a strike on the part of the local Archeus； who refuses to work。 Though full of fanciful ideas； Van Helmont had the experimental spirit and was the first chemist to discov