In his close association with two such men as MacArthur and Reid, Simpson was again fortunate in his environment. The art of medicine was also fortunate inasmuch as at the right moment the right influences were at work to direct his mind towards it. While occupied in mastering the laws of hexameter and iambic or in assimilating the prescribed portion of Virgil and Tacitus, he happily now and then, living with two such enthusiastic medical students, got a taste of the more stimulating study of things scientific--food which was more agreeable to his mental palate, more suited to his mental digestion. By peeps into anatomical books, by little demonstrations of specimens in their lodgings, and by occasional visits to some of the lecture rooms or the wards of the Infirmary, his appetite was whetted for that great study of nature which his youthful training at Bathgate had prepared him for, and for which his mental constitution was specially adapted. One can picture the eagerness with which he would cast aside the finished Greek or Latin essay and urge the not unwilling embryo professor to demonstrate a bone or lecture on an anatomical preparation. Sometimes as a special favour he was taken by Reid to hear one of the lectures of the notorious Robert Knox, the extra-academical teacher of anatomy, whose strong personality and unrivalled powers as a lecturer were at that time attracting to Surgeon's Square hundreds of students, while Munro (Tertius) was mechanically repeating his grandfather's lectures from the University chair. It was towards the end of 1828, when Simpson was just about commencing his medical studies that Edinburgh, and in fact the whole of civilised Europe, was horrified by the revelation of the doings of Burke and Hare, when they were at last brought to justice for the long series of crimes perpetrated for the purpose of selling the bodies of their victims to the anatomical schools. Knox having a class of some four hundred students had special difficulty in meeting the demand for "subjects," and it was brought to light at the trial of Burke that the majority of the bodies were disposed of to Knox. As was only natural, a fierce indignation against Knox sprang up in the city. His residence was assailed and his effigy burnt. His life was in danger at the hands of the mob on more than one occasion. Lord Cockburn in his "Memorials of His Time" says that all the Edinburgh anatomists incurred an unjust and very alarming though not an unnatural odium--Dr. Knox in particular, against whom not only the anger of the populace but the condemnation of more intelligent persons was directed. "But," he says, "tried in reference to the invariable and the necessary practice of the profession our anatomists were spotlessly correct and Knox the most correct of them all."