Shedding new light on Newton's optical writings : Alan Shapiro ed.: The optical papers of Isaac Newton. Volume 1. The optical lectures 1670–1672. Cambridge: Cambridge University Press, 1984, 627 pp, £38.99 PB Alan Shapiro ed.: The optical papers of Isaac Newton. Volume 2. The Opticks (1704) and related papers ca.1688–1717. Cambridge: Cambridge University Press, 2021, 423 pp, £150.00 HB