IV. In the number of causes whereby those modifications (Affectiones. Camerer reads affectus - emotions), are fostered, which have regard to the common properties of things or to God (V:ix., V:xi.). V. Lastly, in the order wherein the mind can arrange and associate, one with another, its own emotions (V:x.Note and V:xii., V:xiii., V:xiv.). But, in order that this power of the mind over the emotions may be better understood, it should be specially observed that the emotions are called by us strong, when we compare the emotion of one man with the emotion of another, and see that one man is more troubled than another by the same emotion; or when we are comparing the various emotions of the same man one with another, and find that he is more affected or stirred by one emotion than by another. For the strength of every emotion is defined by a comparison of our own power with the power of an external cause. Now the power of the mind is defined by knowledge only, and its infirmity or passion is defined by the privation of knowledge only: it therefore follows, that that mind is most passive, whose greatest part is made up of inadequate ideas, so that it may be characterized more readily by its passive states than by its activities: on the other hand, that mind is most active, whose greatest part is made up of adequate ideas, so that, although it may contain as many inadequate ideas as the former mind, it may yet be more easily characterized by ideas attributable to human virtue, than by ideas which tell of human infirmity. Again, it must be observed, that spiritual unhealthiness; and misfortunes can generally be traced to excessive love for something which is subject to many variations, and which we can never become masters of. For no one is solicitous or anxious about anything, unless he loves it; neither do wrongs, suspicions, enmities, &c. arise, except in regard to things whereof no one can be really master.