Book 2
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further, that every disposition is both produced and destroyed by the same things applied in a certain manner, for example health by food and exercises and climate; these points are clear from induction. Therefore goodness too is the sort of disposition that is created by the best movements in the spirit and is also the source of the production of the spirit’s best actions and emotions;
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and it is in one way produced and in another way destroyed by the same things, and its employment of the things that cause both its increase and its destruction is directed towards the things towards which it creates the best disposition. And this is indicated by the fact that both goodness and badness have to do with things pleasant and painful; for punishments, which are medicines, and which as is the case with other curese.g. fever, which is caused by heat, is cured by cold (the contrary doctrine to homoeopathy, similia similibus curantur). operate by means of opposites, operate by means of pleasures and pains.
