Almost the entire history of medicine and surgery illustrates the manner in which physical evils result in physical good. Indeed, men never resort to the physician, or the surgeon, because their remedies and operations are desirable, but only because they are the necessary means of health and comfort. These means are, indeed, for the most part, of human invention, but not, therefore, the less indicative of the divine intention; for they are founded upon such a constitution in nature as makes it possible to discover remedies for disease and accidents. And the characteristics of nature's constitution are an index of the intentions of its Author. The severe mental discipline through which the youth must pass, who would attain distinction in learning, affords us an example of intellectual evil resulting in intellectual wealth and happiness. The trial is too severe for many irresolute minds, and they give over the effort, and sink down into a state of indolence and neglect. But he who bears manfully the discipline will at length gather the golden fruit. And he will be satisfied, too, of the wisdom and benevolence of that law of mental progress, which makes it impossible ever to find a royal road to the temple of learning, and which shuts out from that temple all who shrink from the preparatory discipline. Still more strikingly illustrative of this argument are the evils which men suffer as necessary precursors of moral good. These may be physical or mental; embracing all those experiences that take the name of trials, afflictions, and disappointments. These are often intensely bitter, and they constitute, indeed, the master evils of life. We shudder when we see them coming; and we often writhe in agony when in the furnace. But how many have come out of that furnace purified from base alloy, and ready for the service of God and the world! To do good is henceforth their delight; and they thank God for the severe discipline. When his heavy blows fell upon them, one after another, they felt as if they were the strokes of an incensed Deity. But now they see that they were only the necessary inflictions of infinite love. And they admire the wisdom that could thus educe so much good out of so great evil. I do not contend that good is always educed from evil in this world, or could be; but only that, in a plurality of cases, if men improve the evils they suffer as they might, such would be the effect. And if this be admitted, it is sufficient to establish the general principle, that one of the direct objects of evil in this world is to produce individual benefit. But the converse of this proposition cannot be maintained. We cannot, indeed, deny that evil sometimes results from good; but never as the direct object of the latter. The effect is only incidental; that is, not as the main object; and so a few cases of this sort cannot invalidate the proposition which I defend.