Rome, Summer 1941: a young teacher steadily walked into the classroom of the Italian High School “Visconti”. All the sudents fell in silent and they were very impressed by the countenance of that 24-year-old guy who was talking about Art. His words were very clear and impressive: he was breaking the commonplaces of the Romantic Criticism during the XIX century. That young man was about to become one of the most important founders of the modern art history: his name was Roberto Longhi (1890-1960). The documentary is composed of six lessons (25 minutes each) dealing with the painting from the Byzantines to the Impressionists.