It is 804 centimeters wide and 285 centimeters tall. It was purchased by Cardinal Federico Borromeo in 1626 for six hundred Imperial Lire.
Drawn with charcoal and ceruse, it is the preparatory cardboard used for the School of Athens, a fresco by Raphael that lines the Vatican Rooms, commissioned in 1510 by Pope Julius II. Kept at the Pinacoteca Ambrosiana of Milan, it is the only large piece of Renaissance cardboard that has reached our times in almost integral fashion.
The work represents a congregation of ancient philosophers (Plato, Aristotle, Pythagoras, Socrates, Epicurus) intent on conversing together, and represents the faculty of the soul to know the truth through science and philosophy.
With respect to the painting, the cardboard lacks the background architecture and the figure of Heraclitus, which was added when the painting was practically finished and resembles Michelangelo (sitting in the foreground with his elbow leaning on a marble block). A homage by the painter to his great rival who had just completed the Sistine Chapel.