The theology of Philo is characterized throughout by a tolerant and philosophical grasp of the difficulty of pure monotheism, and of the necessity of a long intellectual searching before the goal can be attained. To declare the Unity of God is simple enough; to have a real conception of it is a very different and a very difficult thing. And Philo's theology has a two-fold aim, in which either part complements the other. It explains, on the one hand, how God is revealed to the world through His powers or attributes or modes of activity, and, on the other, how man can ascend to an ecstatic union with the Real Being through comprehension of those powers. By the ideal ladder which brings down God to earth, man can climb again to Heaven. The three chief rungs of the ladder are the attributes of creation, and of ruling power, and the Logos. The perfect unity of the Godhead is not, of course, properly the subject of attributes, but the limited mind of man so conceives it for its own understanding, and speaks of God's justice, God's goodness, God's wisdom. These are, to use philosophical terminology, categories of the religious understanding, which are finally resolved by the perfect sage in "the synthetic apperception of Unity." Philo follows what may have been a Hebrew tradition in explaining the two names of God, "Elohim" and "Jehovah," as connoting His two chief attributes: (1) the creative or beneficent, (2) the ruling or judicial, or, as it is sometimes called, the law-giving power.[224] Names, as we know, were always regarded by Philo as profound symbols, and naturally the names of God are of vital import; and the twofold expression for the Hebrew Deity, of which the higher critics have made much destructive use, was noticed by the earliest commentators, but made the basis by them of a constructive theology. The ruling and the creative attributes of God are outlined and contained in the highest mode of all, the Logos, "the reason of God in every phase and form of it that is discoverable and realizable by man." For by the Logos, God is both ruler and good.[225] This is the profound interpretation of the story in Genesis, that "God placed at the east of the garden of Eden the two Cherubim and a flaming sword, which turned every way to keep the way of the tree of life" (Gen. iv. 24). The Cherubim are the symbols of the powers of majesty and goodness; the flaming sword is the Logos; "because," says our author quaintly, "all thought and speech are the most mobile and the most ardent (_i.e._, the most intensive) of things, and especially the thought and speech of the only Principle."[226]