The older mystics--eastern and western alike--had laid stress on unity as seen in the nature of God and all things. No one more fully believed in ultimate unity than did Boehme, but he lays peculiar stress on the duality, or more accurately, the trinity in unity; and the central point of his philosophy is the fundamental postulate that all manifestation necessitates opposition. He asserted the uniformity of law throughout all existence, physical and spiritual, and this law, which applies all through nature, divine and human alike, is that nothing can reveal itself without resistance, good can only be known through evil, and weakness through strength, just as light is only visible when reflected by a dark body. Thus when God, the Triune Principle, or _Will_ under three aspects, desires to become manifest, He divides the Will into two, the "yes" and the "no," and so founds an eternal contrast to Himself out of His own hidden Nature, in order to enter into struggle with it, and finally to discipline and assimilate it. The object of all manifested nature is the transforming of the will which says "No" into the will which says "Yes," and this is brought about by seven organising spirits or forms. The first three of these bring nature out of the dark element to the point where contact with the light is possible. Boehme calls them harshness, attraction, and anguish, which in modern terms are contraction, expansion, and rotation. The first two are in deadly antagonism, and being forced into collision, form an endless whirl of movement. These two forces with their resultant effect are to be found all through manifested nature, within man and without, and are called by different names: good, evil and life, God, the devil and the world, homogeneity, heterogeneity, strain, or the three laws of motion, centripetal and centrifugal force, resulting in rotation. They are the outcome of the "nature" or "no" will, and are the basis of all manifestation. They are the "power" of God, apart from the "love," hence their conflict is terrible. When spirit and nature approach and meet, from the shock a new form is liberated, lightning or fire, which is the fourth moment or essence. With the lightning ends the development of the negative triad, and the evolution of the three higher forms then begins; Boehme calls them light or love, sound and substance; they are of the spirit, and in them contraction, expansion, and rotation are repeated in a new sense. The first three forms give the stuff or strength of being, the last three manifest the quality of being good or bad, and evolution can proceed in either direction.