It was a classic moment of serendipity. Catherine, Robert, and I had been filming stories about da Vinci in Milan when we met at a book fair an Italian author, Marco Malvaldi, who has just written a book about da Vinci’s bronze horse statue. In the early 1490s, da Vinci worked on this immense statue of a horse and a rider as a monument to his patron Ludovico Sforza. The statue has never been cast because Sforza used theThe Measure of a Man” bronze to produce cannons for his defense of Milan instead.

In his new book, The Measure of a Man, Malvaldi reveals some engineering innovations and discoveries that da Vinci made while working out how to cast such a huge bronze. At the close of 2019, a year in which we declared da Vinci “Solari’s Hero of the Year,” we are offering you, in the interview below, one more insight into the old master’s unique mind.