and
dedicated his treatise of _La Divina Proporzione_ to Lodovico, describes
the laudable and scientific duel of famous and learned men, that was
held on the 9th of February, 1498, in the Castello of Milan--"that
invincible fortress of the glorious city which is a residence worthy of
His Excellency." The duke himself presided at this meeting, which some
writers have supposed to be a sitting of an academy of arts and sciences
founded by Lodovico, with Leonardo for its president, and left Milan the
next day, on a pilgrimage to the Holy Mount of the Madonna at Varese.
Among the many illustrious personages, religious and secular, who were
present on this occasion, Fra Luca mentions "Messer Galeazzo Sforza di
San Severino, my own special patron," to whom he presented the beautiful
illuminated copy of his treatise, now in the Ambrosiana, the Prior of
the convent of Santa Maria delle Grazie, the doctors and astrologers,
Ambrogio da Rosate, Pirovano, Cusani and Marliani, and many well-known
jurists, councillors, architects, and engineers, including Leonardo da
Vinci, "our fellow-citizen of Florence, who, in sculpture and painting
alike, justifies his name and surpasses"--i.e. _vince_ = conquers--"all
other masters."[72]

Leonardo's Cenacolo, we learn from his friend Pacioli, was at length
finished, and preparations were being made for casting his great horse
in bronze, but the master himself was chiefly engaged in the study of
hydraulics, and was writing a treatise on motion and water-power. In
April, however, he was again painting in the Castello, and Messer
Gualtero, one of Lodovico's most trusted servants, informed the duke,
who was absent for a few days, that both his sons were very well, and
that Magistro Leonardo was at work in the Saletta Negra. He would
shortly proceed to the Camera Grande in the tower, and promised to
complete the decorations by September, in order that the duke might be
able to enjoy them next autumn. A note in one of Leonardo's manuscripts
speaks of twenty-four Roman subjects, probably small decorative groups
in _camaieu_, painted on the vaulting of these rooms, and gives the
exact cost of the blue, gold, and enamel employed, but all trace of
these decorations has vanished. At the same time Lodovico appointed his
favourite master to the post of ducal engineer, and employed him to
survey those vast and elaborate fortifications in the Castello, which
excited the wonder of the French invaders.

Two o