To Sforza

Eccellentissimo Signore mio Duca,

I write to you with the hand that trembles, yet still holds the chisel’s memory, and the weight of bronze that should have been flowing into the mould of the great horse by now. The delay is not one of will but of the earth’s refusal to yield what the fire demands. The clay core, packed as we rehearsed in the foundry at Vigevano, has dried unevenly—where the sun strikes it, the grain loosens like a tongue that will not speak; where the shade holds, it clings too tight, and the wax will not melt clean. The beeswax itself, brought from the hives at Lomello, has softened in the September heat beyond what the formulary allows; it sags in the flanks where the armature bends, and the ribs of the model show through like the lines of a saint’s ribs beneath too-thin flesh. The crucibles, lined with our best refractory clay from the Ticino, crack under the first pour—not all at once, but in slow spider-webs that let the molten metal weep into the sand beneath, staining the floor like a wound that will not close.

I have sent word to Maestro Ambrogio, who oversees the alloying, that we must increase the tin by half a punto more than the old receipt—twenty-two libbre per cento rather than twenty—so that the belly of the beast may hold the fire long enough to settle without tearing. The tin is costly, and the Duke’s purse is not infinite, yet a horse that cracks in the kiln is a horse that serves no one, not even as scrap for cannons. The pattern-makers complain that the new timber from the Val d’Ossola, chosen for its straight grain, warps in the drying shed; they must plane it again, and the shavings smell of resin like a forest on the first day of Creation, before the Fall made thorns.

The bronze itself waits. The coal from the valleys near Novara, which once burned blue and steady, now spits ash like a man with a fever. The bellows groan; the boys who pump them grow thin. I have ordered the purchase of charcoal from the Black Forest, shipped down the Rhine, though the cost is three times what we paid in ’93 when the horse was but a dream on paper. A dream that now weighs as much as a man.

The mould is not ready. The core must be vented again; the gates must be widened where the metal enters the heart, for the wax has left channels too narrow for the bronze to breathe. If we do not widen them, the metal will freeze mid-breath, and the neck of the horse will be hollow as a flute that plays no song.

I have considered the possibility of casting in sections—head, neck, body, legs, tail—then welding the joints with molten metal afterward. But the Duke’s vision was of one seamless beast, a horse that could bear a man’s weight and a banner’s pride without seams to betray weakness. To weld is to admit defeat to the fire, and the fire is not my enemy, though it tests me.

The bronze horse is not delayed by laziness or by lack of reverence for your mandate, Signore mio Duca. It is delayed by the stubbornness of matter, which obeys only those who listen. I listen. The page before me holds the measurements, the angles, the receipts for alloy and flux. It is patient. It does not rush. It does not forget.

When the horse stands whole in the Piazza di Milano, it will be because the earth, the fire, the air, and the water have agreed to let it be. Until then, I remain,

Suo devotissimo servo,

Lionardo, vostro pittore e ingegnere, a servizio di Vostra Eccellenza da più di vent’anni.