The conception of the primary unity of causation which the Hebrew poet reaches through his religion is brought home to us to-day with a vast accumulation of proof by the discoveries of science. The uniformity of law, the co-relation of forces, the analyses of the most diverse and complex organisms into their common chemical elements, the evidence of the spectroscope to the existence of precisely the same elements among the distant stars, as well as the more minute homologies of nature in the animal and vegetable kingdoms, are all irrefutable confirmations of this great truth. Moreover, science has demonstrated the intimate association of what we cannot but regard as good and evil in the physical universe. Thus, while carbon and oxygen are essential elements for the building up of all living things, the effect of perfectly healthy vital functions working upon them is to combine them into carbonic acid, which is a most deadly poison; but then this noxious gas becomes the food of plants, from which the animal life in turn derives its nourishment. Similarly microbes, which we commonly regard as the agents of corruption and disease, are found to be not only nature's scavengers, but also the indispensable ministers of life, when clustering round the roots of plants in vast crowds they convert the organic matter of the soil, such as manure, into those inorganic nitrates which contain nitrogen in the form suitable for absorption by vegetable organisms. The mischief wrought by germs, great as it is, is infinitely outweighed by the necessary service existences of this kind render to all life by preparing some of its indispensable conditions. The inevitable conclusion to be drawn from facts such as these is that health and disease, and life and death, interact, are inextricably blended together, and mutually transformable--what we call disease and death in one place being necessary for life and health in another. The more clearly we understand the processes of nature the more evident is the fact of her unity, and therefore the more impossible is it for us to think of her objectionable characteristics as foreign to her being--alien immigrants from another sphere. Physical evil itself looks less dreadful when it is seen to take its place as an integral part of the complicated movement of the whole system of the universe.
But the chief reason for regarding the prospect with more than satisfaction has yet to be stated. It is derived from the character of Him to whom both the evil and the good are attributed. We can go beyond the assertion that these contrarieties spring from one common origin to the great truth that this origin is to be found in God. All that we know of our Father in heaven comes to our aid in reflecting upon the character of the actions thus attributed to Him. The account of God's goodness that immediately precedes this ascription of the two extreme experiences of life to Him would be in the mind of the writer, and it should be in the mind of the reader also. The poet has just been dwelling very emphatically on the indubitable justice of God. When, therefore, he reminds us that both evil and good come from the Divine Being, it is as though he said that they both originated in justice. A little earlier he was expressing the most fervent appreciation of the mercy and compassion of God. Then these gracious attributes should be in our thoughts while we hear that the mixed experiences of life are to be traced back to Him of whom so cheering a view can be taken.
We know the love of God much more fully since it has been revealed to us in Jesus Christ. Therefore we have a much better reason for building our faith and hope on the fact of the universal Divine origin of events. In itself the evil exists all the same whether we can trace its cause or not, and the discovery of the cause in no way aggravates it. But this discovery may lead us to take a new view of its issues. If it comes from One who is as just and merciful as He is mighty we may certainly conclude that it will lead to the most blessed results. Considered in the light of the assured character of its purpose, the evil itself must assume a totally different character. The child who receives a distasteful draught from the hand of the kindest of parents knows that it cannot be a cup of poison, and has good reason for believing it to be a necessary medicine.