This paper focuses on the philosopher Giovanni Giulietti as the author of textbooks on the history of philosophy. We will reflect on the history of philosophy both as a field of research and a school discipline, not only at universities, but also and above all at high schools: what method should a teacher adopt and what features should a textbook possess in order to communicate the passion for radical investigation into reality, without the history of philosophy becoming a bare chronology of thinkers and movements? Giuseppe Zamboni’s gnoseology provides precious suggestions in order to maintain the critico-theoretical concern which should animate the teaching as well as the study of philosophy, and to ensure that learning is not passive studying, but rather an active dialogue with the true voice of philosophers and with reality.