What we want is facts, not ideas; intelligibility, not profundity—these were the demands with which philosophy was confronted. It was impossible to outflank, in this direction, the representatives of a scientific discipline that admitted of skilful popularisation. There was nothing similar to oppose to it. Philosophers were accordingly compelled to confine themselves to criticism, to show forth the unmistakable defectiveness of the pure-mechanical philosophy, the weaknesses and flaws in its demonstrations and the arbitrary character of its construction; and to point out by a display of much acute reasoning what fifty years before was self-evident, that mind and mental life are not merely an accidental phase of things, not a product incidentally resulting, but an indestructible feature of the inward nature of the world itself. Much of this extensive antimaterialistic literature, in which may also be included by far the greater part of anti-Darwinian literature, can put forth no claim to lasting worth, and is to-day wholly antiquated. For the simple reason that people no longer understand, or at least will soon no longer be able to understand, the circumstances and conditions out of which this polemical activity sprung: namely the transcendent metaphysical philosophy; mistaken idealism which imagined that existence and reality had to be transfigured in and by cognition instead of through will and action; the secret fear of an endangerment or indeed of a dislodgment of the religio-theological world-conception, the supernatural God-idea, the pure spiritual and immortal soul, the freedom of the will, and other phantoms whatsoever the designations they may bear. But this warfare against materialism, which was waged by minds of widely varying rank and power, resulted at least in the substantial advantage of having brought the hostile parties closer together, of having forced them to the reciprocal study of their respective means of investigation, and of having put an end to the complete estrangement that formerly existed between them. Not only did it enrich philosophy, but it also led physical science to a correction of many of its conceptions and to a re-examination of its methodological hypotheses.