It is not my intention to enter on an examination, or even enumeration, of ancient philosophical opinions, nor to show that many of the doctrines which have been brought forward within the last three centuries existed in embryo in those times. It may, however, be observed that, in the midst of much error, there were those who held just views of the various problems of theology, law, politics, philosophy, and particularly of the fundamental doctrines of natural science, the constitution of the solar system, the geological history of the earth, the nature of chemical forces, the physiological relations of animals and plants. It is supposed by many, whose attention has been casually drawn to the philosophical opinions of antiquity, that the doctrines which we still retain as true came to the knowledge of the old philosophers, not so much by processes of legitimate investigation as by mere guessing or crude speculation, for which there was an equal chance whether they were right or wrong; but a closer examination will show that many of them must have depended on results previously determined or observed by the Africans or Asiatics, and thus they seem to indicate that the human mind has undergone in twenty centuries but little change in its manner of action, and that, commencing with the same data, it always comes to the same conclusions. Nor is this at all dependent on any inherent logic of truth. Very many of the errors of antiquity have re-appeared in our times. If the Greek schools were infected with materialism, pantheism, and atheism, the later progress of philosophy has shown the same characters. To a certain extent, such doctrines will receive an impression from the prevailing creeds, but the arguments which have been appealed to in their favor have always been the same. The distinction between these heresies in ancient and modern times lies chiefly in the grosser characters which they formerly assumed, arising partly from the reflected influence of the existing mythology, and partly from the imperfections of exact knowledge. Even the errors of early antiquity are venerable. We must judge our predecessors by the rules by which we hope posterity will judge us, making a generous allowance for the imperfections of reason, the infirmities of character, and especially for the prejudices of the times. To have devoutly believed in the existence of a human soul, to have looked forward to its continuing after the death of the body, to have expected a future state of rewards and punishments, and to have drawn therefrom, as a philosophical conclusion, the necessity of leading a virtuous life--these, though they may be enveloped in a cloud of errors, are noble results of the intellect of man. [Footnote 52: Distinguished as an author in chemistry and physiology, and as a philosophical historian: a native of England, but long a professor in New York University.] * * * * *