It is thus easy to see how the two periods of historical import in medicine at the beginning and end of the Middle Ages may be placed in their intimate relation to Greek influences. At the beginning, Greek medicine was not yet dead in Asia Minor, and it influenced the Arabs. When the revival came, it made itself first felt in the portions of Southern Italy and Southern France where Greek influence had been strongest and still persisted. Fortunately for us, the great Renaissance printers and scholars, themselves touched by the Greek spirit of their time, put the books of the writers of these two periods into enduring printed form, and in more recent years many reprints of them have been issued. These volumes make it possible for us to understand just how thoroughly these colleagues of the Middle Ages faced their problems, and solved them with a practical genius that deserves the immortality that their works have been given.
The history of medicine and surgery during the Middle Ages has been greatly obscured by the assumption that at this time scientific medicine and surgery could scarcely have developed because men were lacking in the true spirit of science. The distinction between modern and medieval education is often said to be that the old-time universities sought to increase knowledge by deduction, while the modern universities depend on induction. Inductive science is often said to be the invention of the Renaissance period, and to have had practically no existence during the Middle Ages. The medieval scholars are commonly declared to have preferred to appeal to authority, while modern investigators turn to experience. Respect for authority is often said to have gone so far in the Middle Ages that no one ventured practically to assert anything unless he could find some authority for it. On the other hand, if there was any acknowledged authority, say Aristotle or Galen, men so hesitated to contradict him that they usually followed one another like sheep, quoting their favourite author and swearing by the authority of their chosen master. Indeed, many modern writers have not hesitated to express the greatest possible wonder that the men of the Middle Ages did not think more for themselves, and above all did not trust to their own observation, rather than constantly rest under the shadow of authority.
Above all, it is often asked why there was no nature study in the Middle Ages — that is, why men did not look around them and see the beauties and the wonders of the world and of nature, and becoming interested in them, endeavour to learn as much as possible about them. Anyone who thinks that there was no nature study in the Middle Ages, however, is quite ignorant of the books of the Middle Ages. Dante, for instance, is full of the knowledge of nature. What he knows about the ants, and the bees, and many other insects; about the flowers, and the birds, and the habits of animals; about the phosphorescence at sea and the cloud effects, and nearly everything else in the world of nature around him, adds greatly to the interest of his poems. He uses all these details of information as figures in his " Divine Comedy," not in order to display his erudition, but to bring home his meaning with striking concreteness by the metaphors which he employs. There is probably no poet in the modern time who knows more about the science of his time than Dante, or uses it to better advantage.
It is sometimes thought that the medieval scholars did not consider that experience and observation were of any value in the search for truth, and that therefore there could have been no development of science. In an article on " Science at the Medieval Universities "* I made a series of quotations from the two great scientific scholars of the thirteenth century, Albertus Magnus and Roger Bacon, with regard to the question of the relative value of authority and observation in all that relates to physical science. Stronger expressions in commendation of observation and experiment as the only real sources of knowledge in such matters could scarcely be found in any modern scientist. In Albert's tenth book of his " Summa," in which he catalogues and describes all the trees, plants, and herbs known in his time, he declares : '6 All that is here set down is the result of our own experience, or has been borrowed from authors whom we know to have written what their personal experience has confirmed; for in these matters experience alone can be of certainty." In his impressive Latin phrase, experimentum solum certificat in talibus. With regard to the study of nature in general he was quite emphatic. He was a theologian as well as a scientist, yet in his treatise on " The Heavens and the Earth," he declared that: " In studying nature we have not to inquire how God the Creator may, as He freely wills, use His creatures to work miracles, and thereby show forth His power. We have rather to inquire what nature with its immanent causes can naturally bring to pass".
* Popular Science Monthly, May, 1911.
Roger Bacon, the recent celebration of whose seven hundredth anniversary has made him ever so much better known than before, furnishes a number of quotations on this subject. One of them is so strong that it will serve our purpose completely. In praising the work done by Petrus, one of his disciples whom we have come to know as Peregrinus, Bacon could scarcely say enough in praise of the thoroughly scientific temper, in our fullest sense of the term, of Peregrinus's mind. Peregrinus wrote a letter on magnetism, which is really a monograph on the subject, and it is mainly with regard to this that Roger Bacon has words of praise. He says : "I know of only one person who deserves praise for his work in experimental philosophy, for he does not care for the discourses of men and their wordy warfare, but quietly and diligently pursues the works of wisdom. Therefore, what others grope after blindly, as bats in the evening twilight, this man contemplates in their brilliancy, because he is a master of experiment. Hence, he knows all of natural science, whether pertaining to medicine and alchemy, or to matters celestial or terrestrial. He has worked diligently in the smelting of ores, as also in the working of minerals; he is thoroughly acquainted with all sorts of arms and implements used in military service and in hunting, besides which he is skilled in agriculture and in the measurement of lands. It is impossible to write a useful or correct treatise in experimental philosophy without mentioning this man's name. Moreover, he pursues knowledge for its own sake; for if he wished to obtain royal favour, he could easily find sovereigns who would honour and enrich him".