If he is already in possession of the truth, he does not require to be put in possession of it. The occupation of philosophy is gone: her office is superfluous. Therefore philosophy assumes and must assume that man does not naturally think aright, but must be taught to do so: that truth does not come to him spontaneously, but must be brought to him by his own exertions. If man does not naturally think aright, he must think, we shall not say wrongly (for that implies malice prepense) but inadvertently: the native occupant of his mind must be, we shall not say falsehood (for that too implies malice prepense) but error. The original dowry then of universal man is inadvertency and error. This assumption is the ground and only justification of the existence of philosophy. The circumstance that philosophy exists only to put right the oversights of common thinking--renders her polemical not by choice, but by necessity. She is controversial as the very tenure and condition of her existence: for how can she correct the slips of common opinion, the oversights of natural thinking, except by controverting them?" Professor Ferrier deserves high commendation for the care taken in this volume to set out clearly Proposition and Counter-Proposition: the thesis which he impugns, as well as that which he sustains.] The number of individual intellects, independent, inquisitive, and acute, is always rare everywhere; but was comparatively less rare in these ages of Greece. The first topic, on which such intellects broke loose from the common consciousness of the world around them, and struck out new points of view for themselves, was in reference to the Kosmos or the Universe. The received belief, of a multitude of unseen divine persons bringing about by volitions all the different phenomena of nature, became unsatisfactory to men like Thales, Anaximander, Parmenides, Pythagoras, Anaxagoras. Each of these volunteers, following his own independent inspirations, struck out a new hypothesis, and endeavoured to commend it to others with more or less of sustaining reason. There appears to have been little of negation or refutation in their procedure. None of them tried to disprove the received point of view, or to throw its supporters upon their defence. Each of them unfolded his own hypothesis, or his own version of affirmative reasoned truth, for the adoption of those with whom it might find favour.