In this paper we will interpret a passage from Aristotle's Metaphysics, 1011a17-1011b, framed in the defense of the Principle of Non-Contradiction and in the criticism of relativist positions that deny it. Our reading is that Aristotle argues that the adequate description of “what appears to someone,” i.e., phenomena, leads to the affirmation of the Principle. Based on the connection of the Principle with the ousia proposed by numerous interpreters, we believe that Aristotle suggests, although without developing it, a “phenomenological way” to achieve the ousia that bears some similarity to the phenomenology of the 20th century.