Some of his observations upon muscles are extremely interesting, and, though he made many mistakes in explaining their function, he added not a little to the anatomical and physiological knowledge of the time in their regard. He seems to have been one of the first to recognize the fact that in the higher animals the heart may continue to beat for a considerable time after the animal is apparently dead; and, indeed, that by irritation of the removed heart, voluntary contractions may be brought about which will continue spontaneously for some moments.
With regard to the objections made by some, that such studies as these upon muscles could scarcely be expected to produce any direct result for the treatment of disease, or in the ordinary practice of medicine, Stensen said in reply that it is only on the basis of the anatomical, physiological, and pathological observation that progress in medicine is to be looked for. In spite, then, of the discouragement of the many, who look always for immediate practical results, Stensen continued his investigation, and even proposed to make an extended study of the mechanism of the muscular action.
In the meantime, however, there had gradually been coming into his life another element which was to prove more absorbing than even his zeal for scientific discovery. It is this which constitutes the essential index of the man's character and has been sadly misunderstood by many of his biographers.
Sir Michael Foster, of Cambridge, England, in his "Lectures on the History of Physiology," originally delivered as the Lane Lectures at Cooper Medical College, San Francisco, said:--
While thus engaged, still working at physiology, Stensen turned his versatile mind to other problems, as well as to those of comparative anatomy, and especially to those of the infant, indeed hardly as yet born, science of geology. His work "De solido intra solidum" is thought by geologists to be a brilliant effort toward the beginning of their science
In 1672 he returned for a while to his native city of [{149}] Copenhagen, but within two years he was back again at Florence; and then there came to him, while as yet a young man of some thirty-six summers, a sudden and profound change in his life.
In his early days he had heard much, too much perhaps, of the doctrines of Luther. Probably he had been repelled by the austere devotion which ruled the paternal roof. And, as his answer to Bossuet shows, his university life and studies, his intercourse with the active intellects of many lands, and his passion for inquiry into natural knowledge, had freed him from passive obedience to dogma. He doubtless, as did many others of his time, looked upon himself as one of the enlightened, as one raised above the barren theological questions which were moving the minds of lesser men
Yet it was out of this sceptical state of mind, that life in Italy and intimate contact with ecclesiastics and religious, so often said to be likely not to have any such effect, brought this acute scientific mind into the Catholic Church. Nor did he become merely a formal adherent, but an ardent believer, and then an enthusiastic proselytizer. One American writer of a history of medicine, in his utter failure to comprehend or sympathize with the change that came over Stensen, speaks of him as having become at the end of his life a mere "peripatetic converter of heretics." This phase of Stensen's life has, however, as ample significance as any that preceded it.
Steno's expectations of the professorship of anatomy at Copenhagen were disappointed, but the appointment went to Jacobson, whose work indeed is scarcely less distinguished than that of [{150}] his unsuccessful rival. The next few years Stensen passed in Paris, where he was assiduous in making dissections, and where he attracted much attention; and then, somewhat later, in Italy; in 1665 and 1666 he was in Rome. Thence he went to Florence, in order to perfect himself in Italian. The next few years he spent in this city, having received the appointment of body physician to the Grand Duke, as well as an appointment of visiting physician, as we would call it now, to the Hospital of Santa Maria Nuova.
It was while at Florence that the whole current of Stensen's life was changed by his conversion to Catholicity. His position as physician to the Hospital of Santa Maria Nuova brought him frequently into the apothecary shop attached to the hospital. As a result he came to know very well the religious in charge of the department, Sister Maria Flavia, the daughter of a well-known Tuscan family. At this time she had been for some thirty-five years a nun. Before long she learned that the distinguished young physician, at this time scarcely thirty years of age, who was such a pleasant gentleman in all his ways, was a Lutheran. She began, as she told afterwards, first by prayer, and then by friendly suggestions, to attempt to win him to the Catholic Church. Stensen, who seems already to have been well-disposed toward the Church, and who had always been known for a wonderful purity of heart and simplicity of character, listened very willingly to the naive words of the [{151}] old religious, who might very well have been his mother.
Many years later, by the command of her confessor, the good Sister related the detailed story of his conversion. She began very simply by telling him one day that if he did not accept the true Catholic faith, he would surely go to hell. He listened to this without any impatience, and she said it a number of other times, half jokingly perhaps, but much more than half in earnest. As he listened so kindly, she said to him one day that he must pray every day to God to let him know the truth. This he promised to do and, as she found out from his servant (what is it these nuns do not find out?) he did pray every evening. One day, while he was in the apothecary shop, the Angelus bell rang, and she asked him to say the Angelus. He was perfectly willing to say the first part of the Hail Mary, but he did not want to say the second part, as he did not believe in the invocation of the Blessed Virgin and the saints. Then she asked him to visit the Church of the Blessed Virgin, the Santissima Nunziata, which he did. After this she suggested to him that he should abstain from meat on Fridays and Saturdays, which he promised to do, and which the good nun found out once more from his servant, he actually did do. And then the religious thought it was time to suggest that he should consult a clergyman, and his conversion was not long delayed.