To read a passage like this separated from its context and without knowing anything about the wonderful powers of observation of the men from whom it comes, it would be very easy to think that it is merely a set of general directions which they had made on some general principle, perhaps quite foolish in itself. We know, however, that these men had by observation detected nearly every feature of importance in fractures of the skull, their indications and contra-indications for operation and their prognosis. They had anticipated nearly everything of importance that has come to be insisted on even in our own time in the handling of these difficult cases. It is not unlikely, therefore, that they had also arrived at the recognition by observations on many patients that the satisfactory after-course of these cases which were operated on by the surgeon after due regard to such meticulous cleanliness as is suggested in the paragraph I have quoted, made it very clear that these aseptic precautions, as we would call them, were extremely important for the outcome of the case and, therefore, were well worth the surgeon's attention, though they must have required very careful precautions and considerable self-denial. Indeed this whole subject, the virtual anticipation of our nineteenth-century principles of aseptic surgery in the thirteenth century, is not a dream nor a far-fetched explanation when one knows enough about the directions that were laid down in the surgical text-books of that time. THE NORTH ITALIAN SURGEONS