The being and coming to be: the perpetual one versus the changeable one Is said that it has much time, Parmnides said on Heraclitus: ' ' It are with the men whom nothing they know and they seem to have two heads! Next to them it is everything, also its thought, in flow. They admire the things perennially but they need to be so deaf how much blind to mix the contrary thus! ' '. In fact, the two original philosophers divergiam in its ontolgicas theories (ontologia is understood as the area of the philosophy that study the being and its dynamic). While Parmnides affirmed that the being never could leave of being what it is in its essence, exactly that passing for changes, Heraclitus said that the being is always in constant change, therefore ' ' If he cannot the same enter two times in rio' ' , as he says one of its fragmentos. But, what he makes the thought of Parmnides to be different of the one of Heraclitus? Parmnides tries to command the reality, making the use of two groups: what they are, and what they are not. For this, it takes as starting point the light. The light is one ' ' ser' ' , and its opposite, the blackout, is not, that is ' is one; ' not ser' ' . For a light, it attributed the value of everything what he is positive, and to the blackout, what it has of negative, as it says the same I break up in it: ' ' But because everything has been nominated as light and darknesses, and this as to leaves proper dynamics each thing in its singularity: everything is full of light and clear blackout of the night, while the same, both the same, therefore nothing ambos' is cited seno; '. So that if something beyond the being exists, that is, of what it is, the existence would become necessary of what it is not.