This brief account of one who must ever hold an honourable place in the history of mathematical science may enable us to value at its true worth the praise which Leonardo bestowed on Michael Scot. It seems that the first edition of the _Liber Abbaci_ was not entirely satisfactory. Scot wrote a letter to the author which possibly contained strictures on the work, and asked that a copy of the emended edition should be sent him. Pisano replied by dedicating the book to his correspondent. It appeared in 1228, and contained a prefatory letter, in which the author addresses Scot in the highest terms of respect, calling him by that title of _Supreme Master_ which he had won at Paris, and submitting the _Liber Abbaci_, even in this its final form, to his further emendation. This _laudari a laudato_ must have been most grateful to the philosopher, and it enables us to see the standing he had among the mathematicians of his time. One would almost be disposed to infer, from the respect Pisano paid him, that Scot himself had composed or translated some lost work on algebra. In another connection we shall find reason to think that this conjecture may be well founded.[217] Besides the practice of astrology and his deeper researches in astronomy and mathematics, Michael Scot devoted himself to another profession, that of medicine. This was then a science very imperfectly understood, yet here too, in the years that followed his return to court, Scot made a name for himself as a physician, and contributed something to the advancement of human knowledge in one of its most important branches. The healing art in Europe had only just begun to emerge from that primitive state in which savage peoples still possess it; overlaid by charms and incantations; the peculiar department of the wise woman, the sorcerer, and the priest. Among the Latin races the lady of the castle and the _bella donna_ of the village still cared for rich and poor in their various accidents and sicknesses, as indeed they continued to do for several ages more. Only crowned heads, the wealthiest of the nobility, or the rich merchants of the cities, began to require and employ the services of regular physicians. These were generally Jews, sometimes Moors;[218] and thus fashion and experience alike began to make popular among our ancestors the superior claims of science in medicine. Such science had undoubtedly survived from the days and in the works of Hippocrates, Galen, and Celsus, and was now preserved in the theory and practice of the Arabian schools.