Such consideration as it is feasible to give the first of these historical propositions in these columns, was, for the most part, included in that portion of the examination of the positions of our two authors, which was contained in the opening paper of the series; though no special application of Principles there elaborated was made to this formula. It was there pointed out, that intellectual forces constitute only _one_ of the factors in the sum of human progress, and that _moral_ forces are equally as important, being the second--the opposite and complementary factor. In the light of that exposition, and of the brief consideration here given to the second Generalization, it is perceptible that the defect in this proposition consists, not in what it affirms, but in what it does _not_ affirm. 'That the progress of mankind depends on the success with which the laws of phenomena are investigated, and on the extent to which a knowledge of those laws is diffused,' is a statement which is undeniably true. It does not, however, contain the _whole truth_ in relation to the subject of investigation. It is just as correct to say that the progress of mankind depends on the success with which the moral or religious faculties--faculties which instigate devotion to our highest perception of right--are cultivated, and on the extent to which they are practically active. For it is not in the inculcation of intellectual truth alone, or preeminently, nor in the cultivation of moral strength alone, or predominantly, that the progress of mankind is secured; but in the developing vigor of _both_ mental and moral forces, and in their mutual cooeperation and assistance.