Since the rise of scientific thinking in the seventeenth century the role of the imagination in literature has been a matter for debate. Is it an essential resource, as maintained by some Romantic writers, or a treacherous purveyor of illusions? In this lecture Professor Beer suggests that one result of this uncertainty has been to set up a division (which continues to pervade literary enterprises) between imaginative flights on the one hand and the 'weighing of words' on the other. His examples are drawn from a wide range of writers, including Johnson and Dickens, Hopkins and Woolf. The lecture concludes with an examination of two poems by Wordsworth, who is seen as having faced these problems in an unusually intricate and subtle manner.