This Book owes its origin to the indefinable sense of uneasiness and discontent into which I was thrown by the perusal of some of the best treatises on Logic. These treatises had failed to explain the nature of the logical or reasoning faculty, though purporting to indicate the laws which govern its proper functioning. Even the work of John Stuart Mill, which still remains in my opinion the best, was no more convincing than the rest. And the more I read of such books the less satisfied I became and the stonger became my desire to understand clearly what constituted reasoning.

As for the psychologists I found to my surprise that they either omitted reasoning altogether, or alluded to it in a most superficial manner.