It would be an injury to the memory of Boerhaave, not to mention what was related by himself to one of his friends, that when he lay whole days and nights without sleep, he found no method of diverting his thoughts so effectual, as meditation upon his studies, and that he often relieved and mitigated the sense of his torments, by the recollection of what he had read, and by reviewing those stores of knowledge, which he had reposited in his memory. This is, perhaps, an instance of fortitude and steady composure of mind, which would have been for ever the boast of the stoick schools, and increased the reputation of Seneca or Cato. The patience of Boerhaave, as it was more rational, was more lasting than theirs; it was that "patientia Christiana," which Lipsius, the great master of the stoical philosophy, begged of God in his last hours; it was founded on religion, not vanity, not on vain reasonings, but on confidence in God. In 1727, he was seized with a violent burning fever, which continued so long, that he was once more given up by his friends. From this time he was frequently afflicted with returns of his distemper, which yet did not so far subdue him, as to make him lay aside his studies or his lectures, till, in 1726, he found himself so worn out, that it was improper for him to continue any longer the professorships of botany or chymistry, which he, therefore, resigned, April 28, and, upon his resignation, spoke a "Sermo academicus," or oration, in which he asserts the power and wisdom of the creator from the wonderful fabrick of the human body; and confutes all those idle reasoners, who pretend to explain the formation of parts, or the animal operations, to which he proves, that art can produce nothing equal, nor any thing parallel. One instance I shall mention, which is produced by him, of the vanity of any attempt to rival the work of God. Nothing is more boasted by the admirers of chymistry, than that they can, by artificial heats and digestion, imitate the productions of nature. "Let all these heroes of science meet together," says Boerhaave; "let them take bread and wine, the food that forms the blood of man, and, by assimilation, contributes to the growth of the body: let them try all their arts, they shall not be able, from these materials, to produce a single drop of blood. So much is the most common act of nature beyond the utmost efforts of the most extended science!" From this time Boerhaave lived with less publick employment, indeed, but not an idle or an useless life; for, besides his hours spent in instructing his scholars, a great part of his time was taken up by patients, which came, when the distemper would admit it, from all parts of Europe to consult him, or by letters which, in more urgent cases, were continually sent to inquire his opinion and ask his advice.