My father and I observed the scene for some moments before the Master finally noticed our presence.

“Ah, Master Angelo,” he exclaimed, giving my father that more formal title now that we were among others. “Let me introduce my assistants to you.”

I felt a rush of pride as my friends made their bows and then listened respectfully while my father, in turn, gave them a brief account of his accomplishments. A few of the boys-Tito and Paolo, I knew for certain-had some knowledge of woodworking and appeared suitably impressed by the commissions my father described. For my part, I stood to one side and contented myself with my good fortune at having been born to a father of such kindness and talent.

When my father returned the floor to the Master, Leonardo said, “If you will recall, draftsmen, I gave you a holiday today. A few more hours yet remain, so again I task you with spending them in some enjoyable manner until it is time for the evening meal.”

A small cheer rose at this, and under the Master’s indulgent smile the youths swiftly scattered. Then he turned to my father and me. “And now, it is time for me to reveal to you the nature of my latest invention, which requires a master cabinetmaker’s skilled touch.”

We returned to his quarters and waited while, with a show of great secrecy, he left us alone and stepped into his private workshop. He reappeared a few moments later, carrying a cloth-covered object perhaps as wide and broad as my arm. Setting it upon the table, he gestured us closer and said, “You must excuse my caution, but I must first make certain that we are not being observed.”

While my father and I exchanged puzzled glances, he checked the door to make certain it was latched and then pulled the shutters closed across the window. What could be beneath this cloth that required such precautions against its being seen? I had been prepared for something substantial, similar to his expandable bridge or his river dredger… perhaps a catapult that tossed flames. Whatever lay hidden beneath that length of oiled linen, however, could hardly be of that scale.

I frowned. It mattered little to me what this invention was, for as Leonardo’s apprentice I was here at his whim. If not here, I would be toiling in the main workshop or smoothing plaster upon yet another wall in the duke’s chambers.

My father, however, was a different matter. He had left behind his own workshop and his own commissions-not to mention my mother and brothers-solely on Leonardo’s word. What promises the Master had made to entice him into the duke’s service, I could not guess, though I knew full well the Master’s persuasive ways. As clever with words as he was with his brush, Leonardo could talk a rabbit into a wolf’s jaws. Still, I could not think that he would bring my father to Milan on a fool’s mission. But from the expression on his face, Angelo della Fazia certainly had traveled all this way in the expectation of seeing something… larger.

“First, I must swear you both to secrecy,” the Master reminded us, seeming unaware of our doubt. “Other than Ludovico himself, no one else has been privy to what I am about to reveal. The fate of Milan -indeed, of the entire world-might rest with this invention. And so, I must have your vows that you will not speak of what I am about to show you with anyone other than ourselves.”

I must point out that Leonardo had been appointed Il Moro’s master of pageantry for a good reason, given that he knew how to add drama to the most mundane moments. He demonstrated that talent now as he paused, his hand upon the cloth, while a look of almost mystic fervor settled upon his handsome features. Despite my earlier doubt, my curiosity was piqued. Perhaps I had been too hasty in my rush to judgment, I told myself as I eagerly gave him my promise of silence.

Nodding, his gaze flicked from me to my father as he awaited a second response. My father was frowning, but I guessed from the inquisitive tilt of his head that he had decided Leonardo would not have brought him all the way to Milan for a trifle.

“Very well, Signor Leonardo, you have my vow, as well. I swear I shall reveal nothing of this matter to anyone else.”

Leonardo gave a satisfied smile. “Then I shall hold you in suspense no longer. But prepare yourselves, for I am about to show you the future,” he declared and snatched away the cloth.

My father and I stared at what appeared at fi rst glance to be a linen and wood crucifi x; however, the requisite Christ figure was posed unlike any I had ever seen. Rather than resting supine with arms stretched wide, he was stretched at length upon his belly, hands and elbows to his sides. As for the crucifix’s crosspiece, it was constructed of cloth laid over delicate ribbed frame that seemed to resemble wings. Not so much those of a bird, perhaps, but more like the scalloped leathery appendages belonging to a bat.

Certainly, this was no religious carving, after all. Then realization struck with a serpent’s swiftness, and I gazed up at Leonardo in wide-eyed disbelief.

It should be said that the Master’s doings were of great interest here at Castle Sforza. From his glorious frescoes, which added color and gaiety to the fortress’s gloomy halls, to the elaborate pageants and parades, which provided feast day entertainment, all were subject to scrutiny by various and sundry of the castle’s inhabitants. Indeed, he was watched and discussed almost as closely as was Il Moro himself.

During the past few weeks, the rumor passed among the castle servants-and always accompanied by a snicker or roll of the eyes-concerned a new machine that they called “Signor Leonardo’s folly.” I’d also overheard the occasional whisper from one apprentice or another who had claimed to have seen a drawing of this marvel. But while I had no doubt that the invention might exist upon paper as part of the Master’s copious output of sketches both whimsical and sublime, I had never believed he would attempt to build it.

And yet, here it lay before my eyes.

Properly awed, I asked in a respectful tone, “Tell me, Master, is this what I think it is?”

“If you think that it is a flying machine,” he replied with a small smile, “then yes, it is.

“A scale model, of course,” he was quick to clarify as my eyes grew wider, “although I have also commenced work on the frame of the man-sized version. Still, there are several modifications that must be made to the design before either craft is deemed flight-worthy. Weight distribution is one issue that I-”

“A flying machine?”

The abrupt question came from my father, his tone incredulous. Worse, his usually placid expression reflected more than a hint of anger. Staring at the Master as if the younger man had taken leave of his senses, my father shook his head.

“Can it be, Signor Leonardo, that you summoned me to Milan on a fool’s errand?” he sputtered. “I thought to be serving the duke on a project of great importance, but you appear to be having a joke at my expense. I think it best that I forget this matter and return home to my own workshop.”

He paused to give me a concerned look and added, “And perhaps I should take my, er, son with me.”

“Father, no,” I cried before the Master could make a reply.

Clutching his tunic sleeve, I persisted, “I cannot leave, and you must stay as well. Signor Leonardo would not jest about such a matter. I have seen with my own eyes many of his wonderful inventions. If he says he can build a machine that flies, I am certain it can be done.”