We have remarked that moral certainty exists only where the harmony of the moral constitution is preserved. Here we know the right will be obeyed. It may be remarked in addition to this, however, that moral certainty may almost be said to exist in the case of the lowest moral degradation, where the right is altogether forsaken. Here the rule is, "whatever is most agreeable;" and the volition is indeed merged into the sense of the most agreeable. But in the intermediate state lies the wide field of probability. What is commonly called the knowledge of human nature, and esteemed of most importance in the affairs of life, is not the knowledge of human nature as it ought to be, but as it is in its vast variety of good and evil. We gain this knowledge from observation and history. What human nature ought to be, we learn from reason. On a subject of so much importance, and where it is so desirable to have clear and definite ideas, the rhetorical ungracefulness of repetition is of little moment, when this repetition serves our great end. I shall be pardoned, therefore, in calling the attention of the reader to a point above suggested, namely, that the will is in a triunity with reason and sensitivity, and, in the constitution of our being, is designed to derive its rules and inducements of action from these. Acts which are in the direction of neither reason nor sensitivity, must be very trifling acts; and therefore acts of this description, although possible, we may conclude are very rare. In calculating, then, future acts of will, we may, like the mathematicians, drop infinitesimal differences, and assume that all acts of the will are in the direction of reason or sensitivity, or of both in their harmony. Although the will is conscious of power to do, out of the direction of both reason and sensitivity, still, in the triunity in which it exists, it submits itself to the general interests of the being, and consults the authority of conscience, or the enjoyments of passion. Now every individual has acquired for himself habits and a character more or less fixed. He is known to have submitted himself from day to day, and in a great variety of transactions, to the laws of the conscience; and hence we conclude that he has formed for himself a fixed purpose of doing right. He has exhibited, too, on many occasions, noble, generous, and pure feelings; and hence we conclude that his sensitivity harmonizes with conscience. Or he is known to have violated the laws of the conscience from day to day, and in a great variety of transactions; and hence we conclude that he has formed for himself a fixed purpose of doing wrong. He has exhibited, too, on many occasions, low, selfish, and impure feelings; and hence we conclude that his sensitivity is in collision with conscience.