A new category of thought has taken possession of the thought of our time—­a category which is fatal to dualism.  The idea of development is breaking down the division between mind and matter, as it is breaking down all other absolute divisions.  Geology, astronomy, and physics at one extreme, biology, psychology, and philosophy at the other, combine in asserting the idea of the universe as a unity which is always evolving its content, and bringing its secret potencies to the light.  It is true that these sciences have not linked hands as yet.  We cannot get from chemistry to biology without a leap, or from physiology to psychology without another.  But no one will postulate a rift right through being.  The whole tendency of modern science implies the opposite of such a conception.  History is striving to trace continuity between the civilized man and the savage.  Psychology is making towards a junction with physiology and general biology, biology with chemistry, and chemistry with physics.  That there is an unbroken continuity in existence is becoming a postulate of modern science, almost as truly as the “universality of law” or “the uniformity of nature.”  Nor is the postulate held less firmly because the evidence for the continuity of nature is not yet complete.  Chemistry has not yet quite lapsed into physics; biology at present shows no sign of giving up its characteristic conception of life, and the former science is as yet quite unable to deal with that peculiar phenomenon.  The facts of consciousness have not been resolved into nervous action, and, so far, mind has not been shown to be a secretion of brain.  Nevertheless, all these sciences are beating against the limits which separate them, and new suggestions of connection between natural life and its inorganic environment are continually discovered.  The sciences are boring towards each other, and the dividing strata are wearing thin; so that it seems reasonable to expect that, with the growth of knowledge, an unbroken way upwards may be discovered, from the lowest and simplest stages of existence to the highest and most complex forms of self-conscious life.

Now, to those persons who are primarily interested in the ethical and religious phenomena of man’s life, the idea of abolishing the chasm between spirit and nature is viewed with no little apprehension.  It is supposed that if evolution were established as a universal law, and the unity of being were proved, the mental and moral life of man would be degraded into a complex manifestation of mere physical force.  And we even find religious men rejoicing at the failure of science to bridge the gap between the inorganic and the organic, and between natural and self-conscious life; as if the validity of religion depended upon the maintenance of their separating boundaries.  But no religion that is free from superstitious elements has anything to gain from the failure of knowledge to relate things to each other.  It is difficult