says that because God is infinite, people can only speak of God by analogy, for some of the aspects of the divine nature are hidden (Deus absconditus) and others revealed (Deus revelatus) to finite human minds. Thomist philosophy holds that we can know about God through his creation (general revelation), but only in an analogous manner. For instance, we can speak of God's goodness only by understanding that goodness as applied to humans is similar to, but not identical with, the goodness of God. Further, he argues that sacred scripture employs figurative language: "Now it is natural to man to attain to intellectual truths through sensible objects, because all our knowledge originates from sense. Hence in Holy Writ, spiritual truths are fittingly taught under the likeness of material things." In order to demonstrate God's creative power, Aquinas says: "If a being participates, to a certain degree, in an 'accident,' this accidental property must have been communicated to it by a cause which possesses it essentially. Thus iron becomes incandescent by the action of fire. Now, God is His own power which subsists by itself. The being which subsists by itself is necessarily one." Anthropology In addition to agreeing with the Aristotelian definition of man as "the rational animal," Aquinas also held various other beliefs about the substance of man. For instance, as the essence (nature) of all men are the same, and the definition of being is "an essence that exists," humans that are real therefore only differ by their specific qualities. More generally speaking, all beings of the same genus have the same essence, and so long as they exist, only differ by accidents and substantial form. Soul Thomists define the soul as the substantial form of living beings. Thus, plants have "vegetative souls," animals have "sensitive souls," while human beings alone have "intellectual" – rational and immortal – souls. The appetite of man has two parts, rational and irrational. The rational part is called the will, and the irrational part is called passion. Ethics Aquinas affirms Aristotle's definition of happiness as "an operation according to perfect virtue", and that "happiness is called man's supreme good, because it is the attainment or enjoyment of the supreme good." Aquinas defines virtue as a good habit, which is a good quality of a person demonstrated by his actions and reactions over a substantial period of time. He writes: Aquinas ascertained the