and immutable laws. This realism is complemented by a corresponding theory of knowledge, according to which reason is the gradual product of an experience more or less long, and gives a faithful representation of the order in the external world. These premises condition the adoption of the 'natural' method, which consists in always reasoning from the physical to the moral, from the inferior to the superior. H. explicitly advocates this method and strictly follows it in his work, rising by degrees from the fundamental laws of matter to the highest principles of the intellectual and social world. The science of ethics crowns the edifice. This science H. considers as the goal of every philosophy. Here, too, we find an essential agreement with empirical and evolutionist morals. Morality is regarded as a part of universal conduct and interpreted physically; the good is reduced to the useful and the useful to the pleasant; moral instinct is explained by experience, heredity, environment, and justified by its happy consequences; optimism and determinism are taught. There is also a singular similarity of spirit, method, and views between the Principles of Sociology and Data of Ethics and the Système de la Nature. In the conception of a problem, in the manner of conducting an explanation and of employing examples, in the turn of the arguments, even in the tone of the discussion, we discover a striking resemblance, and by a singular chance the fundamental idea of this philosophy finds expression in passages which might be called mates. Compare the beginning of the Data of Ethics with the motto of the Systeme de la Nature: "Naturae rerum vis atque majestas in omnibus momentis fide caret, si quis modo partes ejus, ac non totam complectatur animo."
According to Positivism, only facts and laws are knowable, there being neither substances nor causes, hence neither bodies, souls, nor God. But since the observer sees only a narrow field of events and yet feels that there must be an immense mass of phenomena outside of the reach of consciousness, in the past and in the future, the domain of the unknowable is very large. On the Kantian hypothesis, the physical mystery of Positivism disappears, the constancy of natural laws is vouchsafed, but a metaphysical mystery arises. It is impossible to show whether anything objective corresponds to these mental forms. The existence as well as the essence of the soul, the external world and God cannot be known. The realm of the unknowable is impenetrable by reason; faith alone is left us here.
Had Criticism succeeded in overthrowing Empiricism, Kant would be
