It is a cool April afternoon in the year 1687 when I step through the Great Gate of Trinity College. Above me gleams the coat of arms of Henry VIII, and the wind from the Fens carries that damp, green scent known only to Cambridge in spring — a mixture of the waters of the Cam, wet stone, and the first buds of the chestnut trees in the Great Court. A bell strikes three. Students in black robes hurry past, some carrying books beneath their arms, others immersed in heated conversations in Latin, and no one seems to take notice of the gaunt man approaching me by the fountain.