So accomplished is the presentation here of our inner biology, it’s easy to overlook the fact that Leonardo isn’t just progressing anatomical understanding. He is also inventing biological drawing. Today, we live in a world of plentiful biological illustration, and all these methods of explaining the inner body are familiar to us: the section, the inner close-up, the view across the cut, the map of the arteries, the exploded joint. In Leonardo’s time, they all needed to be invented. Here he is, turning abstract knowledge into a tangible and understand­able visual coding.

The final room is dizzyingly impressive. It records his most sustained effort to turn his ­anatomical knowledge into a published treatise. Somehow, he gets to know the professor of anatomy at the university in Pavia, and the two of them embark on a thorough investigation of the skeleton and its muscles. A few of the sheets of intense, insightful drawings that result — a set of views of the inner workings of the human hand; a series of cross sections of the human shoulder in motion; the first accurate drawing of the human spine — are downright miraculous.

These sensitively shadowed drawings of body parts achieve so much more than is demanded of them. There’s a sense of movement, a thoroughly con­­vincing corporeality and, above all, that uniquely Leonardoesque sense that you are somehow able to look through the human skin to a precisely observed inner reality: not an abstracted diagram of the stuff of life, but the stuff itself.

The unobservable is being ob­served here. And this utterly ­convin­cing sense of reality is ­Leonardo the artist’s greatest gift to ­Leonardo the scientist.