In the same lecture Sir James clearly showed the value of studying cases not agreeing with the ordinary types. “We should study all exceptions to rules; never thinking of them as unmeaning or accidental. Especially, we should never use, in its popular but wrong translation, the expression, ‘exceptio probat regulam;’ as if an exception to a rule could be evidence that the rule is right. If we use it, let this be in its real meaning; translating it, as surgeons should, that an exception probes the rule, tests it, searches it—as the Bible says we should ‘prove all things’—to its very boundary.” Finally we may quote some sentences from Sir James Paget’s lecture on “Elemental Pathology,” delivered before the British Medical Association in 1880, as expressing his philosophy of life. “I hold it to be very desirable that every one of us should, all his life long, study some science in a scientific manner. There seems to be no equally good method for maintaining the temper and the habits, which by making us always good students, will make us as good practitioners as we can be. There is no method so good for maintaining a constant habit of inquiry, with accuracy and perseverance in research, the power of weighing evidence, of calmly judging, and of accurately speaking; none better for cultivating the love of truth, the contempt for fallacies, whether others’ or our own, the gentleness and courtesy which are appropriate to the consciousness of the imperfection of our knowledge.” CHAPTER XXI. _WILLIAMS, STOKES, AND DISEASES OF THE CHEST._ Although this country has not enjoyed the distinction of introducing that invaluable instrument, the stethoscope, to medical science, great interest naturally attaches to those who first used the stethoscope in this country. And among these the name of Charles John Blasius Williams is prominent. CHARLES WILLIAMS, the son of a clergyman of a Cardiganshire family, was born early in the present century at Heytesbury in Wiltshire, where his father was perpetual curate, and custos of the Hungerford almshouse, in which he resided. He was educated at home by his father. His early liking for natural science and medicine may be considered to have come through his mother, who was the daughter of a surgeon, also named Williams, at Chepstow, and had been educated by Hannah More’s sisters, and received instruction in reading from Hannah More herself. Before the age of fourteen, having access to some good books on natural philosophy, he had made for himself two electrifying machines, a battery of Leyden jars, a voltaic pile, and several little telescopes, microscopes, kaleidoscopes, and æolian harps. Thomson’s Chemistry enabled him to carry on extended chemical experiments, and to start well at Edinburgh subsequently.