"to go down to the feria"

Hemingway saw his first bullfight in Pamplona in 1923. The excitement of the spectacle left him riveted, and it marked the beginning of many visits to the Spanish cities of Pamplona, Madrid and Valencia, with their great traditions of ferias (festivals), bullfights and bull runs. Naturally, Hemingway's experiences and observations made their way into his fiction, and he remarked in his notebook from that initial trip:

an art not an amusement. In the first place, not going to apologise for bull fighting. Is a tragedy -- not a sport. Have only seen 16 -- hope to see 300 more before I die. Only thing that brings man opposit[e]s of life and death.

In fact, Hemingway is credited with making famous the Running of the Bulls -- which takes place in Pamplona during the Fiesta of San Fermín -- through his 1926 novel, The Sun Also Rises.