That the strength of Sydenham’s understanding, the accuracy of his discernment, and ardour of his curiosity, might have been remarked from his infancy by a diligent observer, there is no reason to doubt; for there is no instance of any man, whose history has been minutely related, that did not, in every part of life, discover the same proportion of intellectual vigour; but it has been the lot of the greatest part of those who have excelled in science, to be known only by their own writings, and to have left behind them no remembrance of their domestick life, or private transactions, or only such memorials of particular passages as are, on certain occasions, necessarily recorded in publick registers.

From these it is discovered, that, at the age of eighteen, in 1642, he commenced a commoner of Magdalen hall, in Oxford, where it is not probable that he continued long; for he informs us himself, that he was withheld from the university by the commencement of the war; nor is it known in what state of life he engaged, or where he resided during that long series of publick commotion.  It is, indeed, reported, that he had a commission in the king’s army, but no particular account is given of his military conduct; nor are we told what rank he obtained, when he entered into the army, or when, or on what occasion, he retired from it.

It is, however, certain, that if ever he took upon him the profession of arms, he spent but few years in the camp; for, in 1648, he obtained, at Oxford, the degree of bachelor of physick, for which, as some medicinal knowledge is necessary, it may be imagined that he spent some time in qualifying himself.

His application to the study of physick was, as he himself relates, produced by an accidental acquaintance with Dr. Cox, a physician, eminent at that time in London, who in some sickness prescribed to his brother, and attending him frequently on that occasion, inquired of him what profession he designed to follow.  The young man answering that he was undetermined, the doctor recommended physick to him, on what account, or with what arguments, it is not related; but his persuasions were so effectual, that Sydenham determined to follow his advice, and retired to Oxford for leisure and opportunity to pursue his studies.

It is evident that this conversation must have happened before his promotion to any degree in physick, because he himself fixes it in the interval of his absence from the university, a circumstance which will enable us to confute many false reports relating to Dr. Sydenham, which have been confidently inculcated, and implicitly believed.  It is the general opinion, that he was made a physician by accident and necessity, and sir Richard Blackmore reports, in plain terms, [preface to his Treatise on the Small Pox,] that he engaged in practice, without any preparatory study, or previous knowledge, of the medicinal sciences; and affirms, that when he was consulted by him what books he should read to qualify him for the same profession, he recommended Don Quixote.