The fashionable disparagement of reason, and exaltation of will, feeling or instinct would be more dangerous in a less scientific age. The Italian metaphysician Aliotta has lately brought together in one survey the numerous leaders in the great “reaction against science,” and they are a formidable band. Pragmatists, voluntarists, activists, subjective idealists, emotional mystics, and religious conservatives, have all joined in assaulting the fortress of science which half a century ago seemed impregnable. But the besieged garrison continues to use its own methods and to trust in its own hypotheses; and the results justify the confidence with which the assaults of the philosophers are ignored. We are told that the scientific method is ultimately appropriate only to the abstractions of mathematics. But nature herself seems to have a taste for mathematical methods. A sane idealism believes that the eternal verities are adumbrated, not travestied, in the phenomenal world, and does not forget how much of what we call observation of nature is demonstrably the work of mind. The world as known to science is itself a spiritual world from which certain valuations are, for special purposes, excluded. To deny the authority of the discursive reason, which has its proper province in this sphere, is to destroy the possibility of all knowledge. Nor can we, without loss and danger, or instinct or intuition above reason. Instinct is a faculty which belongs to unprogressive species. It is necessarily unadaptable and unable to deal with any new situation. Consecrated custom may keep Chinese civilisation safe in a state of torpid immobility for five thousand years; but fifty years of Europe will achieve more, and will at last present Cathay with the alternative of moving on or moving off. Instinct might lead us on if progress were an automatic law of nature, but this belief, though widely held, is sheer superstition.