Descartes, in his Third Meditation, said that God re-created the body at each successive moment. So that time was a form of sustenance. On earth time was marked by the sun and moon, by rotations that distinguished day from night, that had led to clocks and calendars. The present was a speck that kept blinking, brightening and diminishing, something neither alive nor dead. How long did it last? One second? Less? It was always in flux; in the time it took to consider it, it slipped away. In one of her notebooks from Calcutta were jottings in Udayan's hand, on the laws of classical physics. Newton's theory that time was an absolute entity, a stream flowing at a uniform rate of its own accord. Einstein's contribution, that time and space were intertwined. He'd described it in terms of particles, velocities. A system of relations among instantaneous events.