Inaugural Lecture.- Pensée et Prédication.- I -- The Irreducible / In the Individual or in Human Communication'.- The Unique Individual and His Other.- The Irreducible Alienation of the Self.- A Time to Exist on One's Own.- Love of Self: Obstacle or Privileged Means of Encountering Another'.- II -- The Irreducible Personal Nucleus in Human Communication.- Participation or Alienation'.- The Dialectical Conception of Self-Determination.- Phenomenology of Personalistic Morality.- The Self and the Other in the Thought of Edith Stein.- III -- The Irreducible Factor in Human Creativity: Causality, Language, Cognition and Interpretation.- Otherness and Causality.- Le Langage Entre Soi et Autrui.- The 'Founded Act' and the Apperception of Others.- Empathy, A Return to Reason.- The Creative Self and the Other in Man's Self-Interpretation.