A keen sensitivity to the effects of light and color and an interest in defining precise spatial relationships probably encouraged Vermeer to experiment with the camera obscura, an optical device that could project the image of sunlit objects placed before it with extraordinary realism. Although he may have sought to depict the camera's effects in his View of Delft (c.1660; Mauritshuis, The Hague), it is unlikely that Vermeer would have traced such an image, as some commentators have charged. Moralizing references occur in several of Vermeer's works, although they tend to be obscured by the paintings' vibrant realism and their general lack of narrative elements. In his Love Letter (c.1670; Rijksmuseum, Amsterdam), a late painting in which the spatial environment becomes more complex and the figures appear more doll-like than in his earlier works, he includes on the back wall a painting of a boat at sea. Because this image was based on a contemporary emblem warning of the perils of love, it was clearly intended to add significance to the figures in the room.