This text explores the profound ontological and epistemological significance of comparison as a fundamental tool for human orientation in the world and for the reactivity of living systems. The author argues that the capacity to compare and differentiate is not exclusive to humanity but extends back to the very origins of life and perhaps even into the realm of pre-living matter. A central theme is the dialectical relationship between comparison and selection, which are mutually conditioning processes. Drawing on Heidegger's interpretation of the Greek term "legein" and Heraclitus's concept of logos, the text interprets comparison as an active gathering of elements into a unity, preventing the world from dissolving into a mere heap of random objects. This reflection is illustrated by Plato's Demiurge in the "Timaeus", who must actively select and differentiate ideas to impose order on the formless flow of being. Ultimately, the text emphasizes the necessity of an active subject who, through comparison and subsequent selection, constitutes the world as a meaningful and ordered whole.