The following translation of the great work of the lamented James Balmes on Philosophy, was undertaken at my suggestion and recommendation, and thus far I hold myself responsible for it. I have compared a considerable portion of it with the original, and as far as I have compared it, I have found it faithfully executed. The translator appears to me to have rendered the author's thought with exactness and precision, in a style not inferior to his own. I have not added, as was originally contemplated, any Notes to those of the author. To have done so, would have swelled the volumes to an unreasonable size, and upon further consideration, they did not seem to me to be necessary. They would, in fact, have been an impertinence on my part, and the reader will rather thank me for not having done it. The work goes forth, therefore, as it came from the hands of its illustrious author, with no addition or abbreviation, or change, except what was demanded by the difference between the Spanish and English idioms.