4. Through what channels do the noxious _physical_ agents enter the constitution and produce disease? Through the digestive organs and skin, without doubt,—to which may be added the lungs, which may imbibe the principles of disorder with the oxygen from the air we breathe. 5. But there is a great class of _moral_ causes of diseases, acting on the body through the medium of the mind—a class so extensive that PLATO considered it to be the origin of all corporeal maladies! 6. Against these moral agents the great spas possess powerful auxiliary counter-agents, _as preventives_, in the form of amusements on the spot and abstraction from cares. They also present the means of removing (if removeable) the effects which these moral causes have already inflicted on the bodily frame. 7. The far greater number of physical remedies act by altering and improving disordered functions and secretions—by evacuation—and by imparting tone to debilitated organs or the whole constitution. 8. It must be allowed that mineral waters contain, to a very considerable extent, the requisite ingredients for fulfilling one or all of the foregoing indications. 9. It is often found to be beneficial to combine tonics, alteratives, and aperients in the same formula or prescription, in order that the three indications alluded to, may be simultaneously accomplished.[77] It is undeniable that some of the spas contain within themselves this combination of chalybeates, aperients, and alteratives, either of which ingredients can be increased at pleasure on the spot. 10. The medicinal agents in the mineral waters, though in much smaller quantities than when given in prescriptions, have a much better chance of success, in consequence of their being so largely diluted by the hand of Nature, and the temperature of the diluent being so very high, in most of the springs. 11. The early hours, and the exercise taken while drinking mineral waters, have powerful influence in promoting their salutary operation. How many invalids, in England, would start from their beds at five o’clock in the morning, to drink salt and water till seven or eight o’clock, using their limbs all the time in locomotion? very few! 12. The warm bathing, which generally precedes or accompanies the drinking of the waters, has also great effect in augmenting the medicinal agency of the waters taken internally. The circulation is drawn to the surface—the insensible perspiration augmented—and various internal organs sympathise with the skin and are relieved from habitual congestion. 13. The habit of early rising, which is unavoidable at the great spas, leads to many other good habits. Early meals and early bed-going follow of course, and of consequence. The excursions in the middle of the day, undertaken while devoid of care, and free from business, contribute not a little to the efficacy of the spas, and to soundness of repose at night.