There have been reasons, no doubt, for such an exclusion; and I am not asserting that either Free Trade or free inquiry is always and under all circumstances to be desired. But it is needful to point out yet once more how plausible the reasons for discouraging some novel research have often seemed to be, while yet the advance of knowledge has rapidly shown the futility and folly of such discouragement.

It was the Father of Science himself who was the first to circumscribe her activity. Socrates, in whose mind the idea of the gulf between knowledge and mere opinion attained a dominant intensity which impressed itself on all ages after him, - Socrates expressly excluded from the range of exact inquiry all such matters as the movements and nature of the sun and moon. He wished - and as he expressed his wish it seemed to have all the cogency of absolute wisdom - that men's minds should be turned to the ethical and political problems which truly concerned them, - not wasted in speculation on things unknowable - things useless even could they be known.

In a kindred spirit, though separated from Socrates by the whole result of that physical science which Socrates had deprecated, we find a great modern systematiser of human thought again endeavouring to direct the scientific impulse towards things serviceable to man; to divert it from things remote, unknowable, and useless if known. What, then, in Comte's view, are in fact the limits of man's actual home and business? the bounds within which he may set himself to learn all he can, assured that all will serve to inform his conscience and guide his life? It is the solar system which has become for the French philosopher what the street and market-place of Athens were for the Greek. And this enlargement (it need hardly be said) is not due to any wider grasp of mind in Comte than in Socrates, but simply to the march of science; which has shown us that the whole solar system does, in fact, minister to our practical needs, and that the Nautical Almanack demands for its construction a mapping of the paths of those ordered luminaries which in the time of Socrates seemed the very wanderers of Heaven.

I need not say that Comte's prohibition has been altogether neglected. No frontier of scientific demarcation has been established between Neptune and Sirius, between Uranus and Aldebaran. Our knowledge of the fixed stars increases yearly; and it would be rash to maintain that human conduct is not already influenced by the conception thus gained of the unity and immensity of the heavens.

To many of the comments that have been made on our work, even by men who are not formal Comtists, the above reflections furnish a fitting reply. But it is not only, nor perhaps mainly, on account of the remoteness of our subject, or its unimportance to human progress, that objection is taken to our inquiry. The criticisms which have met us, from the side sometimes of scientific, sometimes of religious orthodoxy, have om-bodied, in modernised phraseology, nearly every well-worn form of timid protest, or obscurantist demurrer, with which the historians of science have been accustomed to give piquancy to their long tale of discovery and achievement. It would have been convenient had these objections been presented to us in a connected and formal manner. But this has not been the case; and, in fact, they are in their very nature too incoherent, too self-contradictory, for continuous statement. Sometimes we are told that we are inviting the old theological spirit to encroach once more on the domain of science; sometimes that we are endeavouring to lay the impious hands of Science upon the mysteries of Religion. Sometimes we are informed that competent savants have already fully explored the field which we propose for our investigation; sometimes that no respectable man of science would condescend to meddle with such a reeking mass of fraud and hysteria.

Sometimes we are pitied as laborious triflers who prove some infinitely small matter with mighty trouble and pains; sometimes we are derided as attempting the solution of gigantic problems by slight and superficial means.

§ 4. The best way of meeting objections thus confused and contradictory will be to show as clearly as we can at what points our inquiries touch the recent results of science; what signs there are which indicate the need of vigorous advance along the lines which we have chosen. We shall show, perhaps, that there is a kind of convergence towards this especial need - that in several directions of research there is felt that kind of pause and hesitancy which is wont to precede the dawn of illuminating conceptions. We shall not, of course, thus prove that our own attempt has been successful, but we shall prove that it was justified; that if the problems which we set ourselves to solve are found to be insoluble, the gaps thus left in the system of thought on which man's normal life is based will be such as can neither be ignored nor supplied, but will become increasingly palpable and increasingly dangerous.

Let us consider how far this remark can be justified with regard to some of the leading branches of human knowledge in turn. And let us take first Biology, the science which on the whole approaches the closest to our own inquiries. Biology has, during the last half-century, made an advance which, measured by the hold exercised on the mass of cultivated minds, has perhaps had no parallel since the forward stride of astronomy and physics in the days of Newton. A glance at the text-books of the last generation, in physical or mental science - Whewell's History of the Inductive Sciences, or Mill's Logic, - as compared, for instance, with the works of their immediate successor, Mr. Herbert Spencer, shows something which is not so much progress as revolution - the transformation of Biology from a mere special department of knowledge into the key to man's remotest history, the only valid answer to the profoundest questions as to his present being.