However, to avoid committing ourselves to more than is yet proved, we must be content with saying that such are the law and the cause of all progress that is known to us.  Should the Nebular Hypothesis ever be established, then it will become manifest that the Universe at large, like every organism, was once homogeneous; that as a whole, and in every detail, it has unceasingly advanced towards greater heterogeneity; and that its heterogeneity is still increasing.  It will be seen that as in each event of to-day, so from the beginning, the decomposition of every expended force into several forces has been perpetually producing a higher complication; that the increase of heterogeneity so brought about is still going on, and must continue to go on; and that thus Progress is not an accident, not a thing within human control, but a beneficent necessity.

A few words must be added on the ontological bearings of our argument.  Probably not a few will conclude that here is an attempted solution of the great questions with which Philosophy in all ages has perplexed itself.  Let none thus deceive themselves.  Only such as know not the scope and the limits of Science can fall into so grave an error.  The foregoing generalisations apply, not to the genesis of things in themselves, but to their genesis as manifested to the human consciousness.  After all that has been said, the ultimate mystery remains just as it was.  The explanation of that which is explicable, does but bring out into greater clearness the inexplicableness of that which remains behind.  However we may succeed in reducing the equation to its lowest terms, we are not thereby enabled to determine the unknown quantity:  on the contrary, it only becomes more manifest that the unknown quantity can never be found.

Little as it seems to do so, fearless inquiry tends continually to give a firmer basis to all true Religion.  The timid sectarian, alarmed at the progress of knowledge, obliged to abandon one by one the superstitions of his ancestors, and daily finding his cherished beliefs more and more shaken, secretly fears that all things may some day be explained; and has a corresponding dread of Science:  thus evincing the profoundest of all infidelity—­the fear lest the truth be bad.  On the other hand, the sincere man of science, content to follow wherever the evidence leads him, becomes by each new inquiry more profoundly convinced that the Universe is an insoluble problem.  Alike in the external and the internal worlds, he sees himself in the midst of perpetual changes, of which he can discover neither the beginning nor the end.  If, tracing back the evolution of things, he allows himself to entertain the hypothesis that all matter once existed in a diffused form, he finds it utterly impossible to conceive how this came to be so; and equally, if he speculates on the future, he can assign no limit to the grand succession of phenomena ever unfolding themselves before him.  On the other hand, if he looks inward, he perceives that both terminations of the thread of consciousness are beyond his grasp:  he cannot remember when or how consciousness commenced, and he cannot examine the consciousness that at any moment exists; for only a state of consciousness that is already past can become the object of thought, and never one which is passing.