But my main object in relating the story is answered if I have succeeded in clearly pointing out to the reader one of the avenues through which light found its way to my benighted intellect, and led me to reflection on the whole subject of health and disease. Here was obviously one cause of a frequent but most painful complaint. It was natural, perfectly natural, that by this time I should begin to inquire. Have all diseases, then, their exciting causes? Many certainly have; and if many, perhaps all. At least, how do we know but it may be so? And then again, if the causes of chilblains are within our control, and this troublesome disease might be prevented, or its severity mitigated if no more, why may it not be so with all other diseases? To revert for a moment to the case of Lydia Maynard. Though I was the cause, in a certain sense, of her suffering, yet it was a sin of ignorance. But it taught me much wisdom. It made me cautious ever afterward. I do not doubt but I have been a means of preventing a very considerable amount of suffering in this form, since that time, by pointing out the road that leads to it. Prevention is better than cure, was early my motto, and is so still. And from the day in which I began to open my eyes on the world around me, and to reason from effects up to their causes, I have been more and more confirmed in the belief that mankind as a race are to be the artificers of their own happiness or misery. All facts point in this direction, some of them with great certainty. And facts, everywhere and always, are stubborn things. CHAPTER XIII. HOW TO MAKE ERYSIPELAS. My periodical tendency to a species of eruptive disease closely resembling measles, was mentioned in Chapter IV. During the summer of 1823 this affection became unusually severe, and seemed almost beyond endurance. The circumstances were as follows:-- I had in charge a large and difficult school. The weather was very hot, and I was not accustomed to labor in summer within doors. Besides, my task was so difficult as to call forth all the energies of body and mind both; and the "wear and tear" of my system was unusually great. It was in the very midst of these severe labors, in hot and not well-ventilated air, that the eruption appeared. Perhaps it was aggravated by my diet, which, in "boarding around," was of course not the best. The eruption not only affected my body and reached to the extremities, but was accompanied by an itching so severe that I was occasionally compelled to lie awake all night. My general strength at last began to give way under it, and I sought the advice of our family physician.