W.B. Yeats is generally considered to be one of the twentieth century's key English-language poets. He can be considered a Symbolist poet in that he used allusive imagery and symbolic structures throughout his career. Yeats chooses words and puts them together so that in addition to a particular meaning they suggest other meanings that seem more significant. His use of symbols is usually something physical which is used both to be itself and to suggest other, perhaps immaterial, timeless qualities. Yet, unlike most modernists who experimented with free verse, Yeats was also a master of the traditional verse forms. The impact of modernism on his work can be seen in the increasing abandonment of the more conventionally poetic diction of his early work in favor of the more austere language and more direct approach to his themes that increasingly characterises the poetry and plays of his middle period, comprising the volumes In the Seven Woods, Responsibilities and The Green Helmet. His later poetry and plays are written in a more personal vein, and the works written in the last twenty years of his life include mention of his son and daughter, as well as meditations on the experience of growing old. In his poem, The Circus Animals' Desertion, he describes the inspiration for these late works:

Now that my ladder's gone

I must lie down where all the ladders start

In the foul rag and bone shop of the heart