In the preface to Part 5 of the Ethics Spinoza promises to explain “the power of the mind, or of reason” and to “show, above all, how great its dominion over the affects is, and what kind of dominion it has for restraining and moderating them.” This is an important task because of the ethical significance that Spinoza accords to reason. For example, Spinoza writes, “Acting absolutely from virtue is nothing else in us but acting, living, and preserving our being . . . by the guidance of reason. (4p24)” / In other words, Spinoza identifies acting virtuously with acting rationally. Spinoza also identifies acting by the guidance of reason and freedom: “we . . . easily see what the difference is between a man who is led only by an affect, or by opinion, and one who is led by reason. For the former, whether he will or no, does those things he is most ignorant of, whereas the latter complies with no one's wishes but his own, and does only those things he knows to be the most important in life, and therefore desires very greatly. Hence, I call the former a slave, but the latter, a free man. (4p66s)”