My duty in editing this volume is a very simple one:-to state, with frankness and precision, the circumstances of its publication, and, if need be, to disarm criticism by the absence of any thing like pretension on the part of him whose posthumous work is now given to the reading world of his own countrymen. Immediately on my brother's death in the autumn of last year, or as soon (and with me it was very soon) as all hope of possible rescue had faded away, my attention was turned to his manuscript lectures, delivered in different courses at the University of Pennsylvania. I knew that, as popular lectures, or rather essays at lectures, they had been very successful, and I hoped and believed they would bear the severer test of being printed. This, I was well aware, is not always the case; and I examined these manuscripts with the idea of possible inaptitude clearly in my mind. The result, however, was a conviction that these Lectures, or a portion of them, ought to be published. They contain, aside from their value as works of criticism, developments of the pure taste and gentle feeling of the author, which will interest, at least his friends, and be appreciated by all who value them exactly for what they were designed-not profound disquisitions, but popular
