Cycle of Opposites Argument

Plato based his arguments on the basic observation that everything in nature appears because of the two opposite forces which are already expressed on a subatomic level। What is known as the Yin and Yang is found on all levels of our material world. We find it as negative and positive, hot and cold, electron and proton, good and evil, just and unjust, up and down, and so on. If someone becomes unjust or evil, he must have been a good or just person before he turned bad, otherwise he was already bad and could not have turned bad. If someone turns into a good and just person, he must have been the opposite before. If something gets cold it must have been hot before. One enters sleep after being awake and vice versa.