Psychologia Empirica

[con]jecturing the morals of men, empirical psychology provides an unexpected use: this will be clearly evident when we shall establish the foundations of this Art in universal practical philosophy and shall treat in moral philosophy of the signs of virtues and vices, which lead to divining the internal state of the mind. Politics treats of the management of affairs. We derive civil doctrine from natural law and moral philosophy as from more immediate principles. Wherefore, since there is much use for psychology in the law of nature and moral philosophy, it redounds into moral philosophy by means of the precepts of natural law and ethics. Indeed, there is no need that we should appeal to this mediate use; for it has a most excellent immediate use in civil philosophy, not only where the Prince’s care regarding the soul of his subjects is concerned, but also in other chapters of the same: just as will be manifest when we shall expose Politics to the public light. There remains a wholly distinguished use, which alone could commend empirical psychology, nay, demonstrate its indispensable necessity, namely, that which is observed in natural theology.