An emotion which is a passion is a confused idea. If, therefore, we form a clear and distinct idea of this emotion, the idea will not be distinguished--except by reason--from this emotion, in so far as the emotion is related to the mind alone, and therefore the emotion will cease to be a passion. In proportion, then, as we know an emotion better is it more within our control, and the less does the mind suffer from it. Those things which are common to all cannot be otherwise than adequately conceived and therefore there is no modification of the body of which we cannot form some clear and distinct conception. Hence it follows that there is no emotion of which we cannot form some clear and distinct conception. For an emotion is an idea of a modification of the body, and this idea therefore must involve some clear and distinct conception. Since nothing exists from which some effect does not follow, and since we understand clearly and distinctly everything which follows from an idea which is adequate in us, it is a necessary consequence that every one has the power, partly at least, if not absolutely, of understanding clearly and distinctly himself and his emotions, and consequently of bringing it to pass that he suffers less from them. We have therefore mainly to strive to acquire a clear and distinct knowledge as far as possible of each emotion, so that the mind may be led to pass from the emotion to think those things which it perceives clearly and distinctly, and with which it is entirely satisfied, and to strive also that the emotion may be separated from the thought of an external cause and connected with true thoughts. Thus not only love, hatred, etc., will be destroyed, but also the appetites or desires to which the emotion gives rise cannot be excessive. For it is above everything to be observed that the appetite by which a man is said to act is one and the same appetite as that by which he is said to suffer. For example, we have shown that human nature is so constituted that every one desires that other people should live according to his way of thinking, a desire which in a man who is not guided by reason is a passion which is called ambition, and is not very different from pride; while, on the other hand, in a man who lives according to the dictates of reason it is an action or virtue which is called piety. In the same manner, all the appetites or desires are passions only in so far as they arise from inadequate ideas, and are classed among the virtues whenever they are excited or begotten by adequate ideas; for all the desires by which we are determined to any action may arise either from adequate or inadequate ideas. To return, therefore, to the point from which we set out: there is no remedy within our power which can be conceived more excellent for the emotions than that which consists in true knowledge of them, since the mind possesses no other power than that of thinking and forming adequate ideas, as we have shown above.