can now be laid bare as in the dissecting room: great joints can be opened up and closed again with almost every fibre in its original position: the abdomen is opened without cutting its muscular walls: the brain is exposed, not through a hole of say an inch in diameter, but by turning down the side of the skull like the lid of a box and replacing it at the end of our operation; even the heart itself has of late been similarly dealt with. The perfection of asepsis has so wholly altered our methods that the greatest advances in the mechanical art of surgery in my day have I think been due to a freedom of action and an exposure of the field of operation which were formerly incredible.
Following this accuracy of dissection we take a further step which has also greatly assisted the evolution of our art. We now obtain a complete view of the effects of disease and of diseased areas which our predecessors did not possess and dared not seek, and in this way modern surgical operations have taught us much of the real nature of disease. So long as treatment is confined to the use of drugs or to a few comparatively simple operations with a minimum of anatomical dissection we rarely become thoroughly acquainted with pathological processes: the affected parts are never seen during life and we have either no visual knowledge of them at all or such knowledge as we do possess is derived from an examination made after death, when the ultimate stage alone is seen, and seen under conditions far different from those of life. But let surgery enter the field and we acquire at once an actual concrete picture, certainty replaces conjecture and we act with confidence instead of groping in the dark. How many centuries of "clinical observation" went by without the recognition of appendicitis, of the results of pyloric obstruction, or of the diseased conditions of the gall bladder. But now that the surgeon has fully explored the once dreaded