Initially, we present the theory of Democritus and Leucippus whereby being is not more than the not-being(non-being), in contrast to Eleatic ideas about the necessary inexistence of the not-being. This discussion leads us to the opposition between the whole (full) and the empty, which will then be transposed into the opposition between being and nothingness (or not-being). Thus, the opposition between wholeand the empty is an opposition that moves to beingand not-being. Finally, we will make an assessment of the Kantian pre-critical essay Attempt to introduce the concept of negative magnitude into philosophy, in which we recognize a kind of opposition that, as we believe, would be interpreted as being in agreement with the position of Democritus and Leucippus regarding the ontological status of the not-being as an equivalent principle to the being, understood here not as a mutual contradiction in a purely logical sense.
ancient atomism; Eleatism; ontology