As Professor of the Theory of Physic, Gregory had shown remarkable gifts, but in his new subject his teaching was superb. Sir Robert Christison in his autobiography, says of him, ‘Equal in fluency as in choice of language, he surpassed all lecturers I have ever heard. His doctrines were set forth with great clearness and simplicity in the form of a commentary on Cullen’s _First Lines of the Practice of Physic_. His measures for the cure of disease were sharp and incisive. In acute diseases there was no ‘médecine expectante’ for Gregory, he somehow left us with the impression that we were to be masters over nature in all such diseases, that they must of necessity give way before the physician who is early enough and bold enough in encountering them.’ He had a memory so clear that he was never known to forget a case, and in his lectures he made his students see not only the general features of a disease, but an actual case of it which had come under his care. He used stories and history, and his own experience to vivify his lectures, and no doubt he succeeded for he had seen many sides of life. He never had time for more than two-thirds of his subject in one course, but whatever he missed out he always discussed fevers and inflammations. In much that he taught he was in advance of his age. In observing how frequently rheumatic fever tends to heart disease; in limiting the use of blood-letting[8] at a time when it was becoming almost a universal panacea with doctors, in urging a liberal dietary in certain stages of consumption, and in the invention and use of his mixture he showed that his views were in advance of those held by most of his brother physicians. Professor Gregory had an odd habit of wearing his cocked hat while he lectured. Footnote 8: In whole classes of cases, however, Gregory was a decided advocate of blood-letting. It was in the summer of 1796 that dear old Thomas Reid, who was becoming very frail, was induced to pay a visit to St Andrew’s Square, to which Gregory had migrated. His daughter, Mrs Carmichael, was anxious to have the opinion of Dr Gregory, as to whether there was anything she could do to retard the bodily decay which increased daily in her father. It was a happy time to them all. Gregory delighted in the keenness of the old man’s mind. As he was not fit for much exercise, he passed his time in solving algebraical problems, and discussing abstruse subjects with Dugald Stewart. Gregory was no doubt busy. His practice increased daily, and besides this, he probably spent a good deal of his time in the house of Mr M’Leod of Geanies, the Sheriff of Ross-shire; to whose daughter, Isabella, he was married on the 19th of October, just ten days after Thomas Reid’s death.