What exactly exists - a concrete thing or a general concept about it? The lecture will examine Aristotle's early work and his dispute with Plato. The philosophical dispute between Plato and Aristotle begins with the question of what to consider real: a separate thing or a general concept to which we relate it. In the lecture, participants will turn to Aristotle's early writing and explore how he reinterpreted one of his teacher's central ideas. At the center of the discussion will be the distinction between "first" and "second substances." Aristotle refers to first substances as individual things - a specific person, object, or living being. Second substances are the kinds and species, that is, more general concepts through which we describe individual objects. For Aristotle, they are secondary: they do not exist separately but arise as a way to generalize the properties of concrete things. This is where the divergence with Plato occurs, who thought of ideas as primary in relation to the things of the physical world. Aristotle connects the general with the things themselves and does not place it in a separate reality. The lecture will be led by Konstantin Kazachenko - a philosophy lecturer and a graduate of the philosophy faculty of RGGU. Ideas on where to go in Moscow are gathered on our website.