"How much has he taken in the aggregate?" is practically not an equivalent of the first question. I have found an absolutely incurable opium-eater who had never used more than ten grains of morphia _per diem;_ but he had been taking it habitually for a dozen years. In another case the patient had for six months repeated before each meal the ten-grain dose which served the other all day; but he was a man whose pluck under pain equalled that of a woman's, and after a fortnight's anguish of such horror that one could scarcely witness it without being moved to tears, came out into perfect freedom. The former patient, although he had never in any one day experienced such powerful effects from opium as the latter, had used the drug so long that every part of his system had reconstructed itself to meet the abnormal conditions, and must go through a second process of reconstruction, without any anodyne to mask the pain resulting from its decomposition, before it could again tolerate existence of the normal kind. If opium were not an anodyne the terrible structural changes which it works would cause no surprise; it would be _felt_ eating out its victim's life like so much nitric acid. During the early part of the opium-eater's career these structural changes go on with a rapidity which partly accounts for the vast disengagements of nervous force, the exhilaration, the endurance of effort, which characterize this stage, later to be substituted by utter nervous apathy. By the time the substitution occurs something has taken place throughout the physical structure which may be rudely likened to the final equilibrium of a neutral salt after the effervescence between an acid and an alkali. So to speak, the tissues have now combined with their full equivalent of all the poisonous alkaloids in opium. Further use of it produces no new disengagements of nervous force; the victim may double, quadruple his dose, but he might as well expect further ebullition by adding more aqua-fortis to a satisfied nitrate as to develop with opium exhilarating currents in a tissue whose combination with that drug have already reached their chemical limit. [Footnote: I say "chemical" because so much it is possible to know experimentally; and the very interesting examination of such higher forces as constantly seem to intrude in any nervous disturbance would here involve the discussion of a theoretical "vital principle"--something apart from and between the soul and physical activities--which scientific men are universally abandoning.]