Chapter 1 explores Woolf’s writings up to the end of 1925 in relation to scientific ideas on wave-particle duality, providing the ‘retrospect of Woolf’s earlier novels’ which Michael Whitworth has suggested shows that she was working ‘in anticipation of the physicists’. The chapter as a whole challenges this idea of anticipation, showing that Woolf was actually working in parallel with physicists, philosophers, and artists in the early twentieth century, all of whom were starting to question dualistic models and instead beginning to develop complementary ones. A retrospect on wave-particle duality is also provided, making reference to Max Planck’s work on quanta and Albert Einstein’s development of light quanta. This chapter pays close attention to Woolf’s writing of light and her use of conjunctions, suggesting that Woolf was increasingly looking to write ‘both/and’ rather than ‘either/or’. Among other texts, it considers Night and Day, Mrs Dalloway, and ‘Sketch of the Past’.