In the example of this particular painting, from 1915, Waterhouse made use of inspiration from the literature of Tennyson, an English poet of several generations previous. Interestingly, the artist actually made use of The Lady of Shalott for several different artworks, including this one and the world-famous The Lady of Shalott which continues to spearhead his oeuvre, a century later.
I am Half-Sick of Shadows quotes directly from towards the end of the poem. It features a young lady sat at her desk, completing some embroidery whilst thinking deeply about more significant matters. It is now housed in the Art Gallery of Ontario in Toronto and is one of several Waterhouse paintings to be owned outside of Europe.
A further examination of the story itself reveals more about the painting - she is actually trapped in a tower at this point and is forced to weave a tapestry in order to occupy her mind whilst waiting for freedom. Thankfully, Lancelot would later appear to entice her from the tower and create a happy ending.
The background elements of this piece continue the artist's preference for Roman-style building work, rather than Gothic. There is also a geometric pattern across the floor that he repeats in several other indoors scenes. The atmosphere of a young woman embroidering a design is charming to most and sums up the style of the Pre-Raphaelite movement.