In central France in the 11th century, a young monk looked up at the dark sky. His job was to ring the monastery bells at set hours through the night. He could tell the time by the movement of the stars, which he recorded in a small notebook. On Christmas Day, he had to ring the bells when Gemini was above the dormitory and Orion above the chapel. On the feast of St Vincent, he had to watch for the scales of Virgo to appear over a certain window. But – ‘note this carefully’, he cautioned in his book – in order to see that window, he had to step back a little towards the juniper bush on the path leading to the well.
The ability to track the stars was fundamental to the rhythms and routines of daily life in the Middle Ages. This was not science in isolation. It had a purpose. Understanding the night sky meant being a step closer to understanding God, but it also meant that the seasons could be known and that there would be food on the table.
The Light Ages shows medieval science in exactly this way, from the vast and the abstract (the movement of the heavens; the nature of free will and destiny) to the practical and everyday (the patterns of the tides; the invention of spectacles). Science had a broad meaning in the Middle