Found at this site :

"In those years Dickinson experienced a painful and obscure personal crisis, partly of a romantic nature. The abject and pleading drafts of her second and third letters to the unidentified person she called "Master" are probably related to her many poems about a loved but distant person, usually male. There has been much speculation about the identity of this individual. One of the first candidates was George Henry Gould, the recipient in 1850 of a prose Valentine from Dickinson. Some have contended that Master was a woman, possibly Kate Scott Anthon or Susan Dickinson. Richard Sewall's 1974 biography makes the case for Samuel Bowles. All such claims have rested on a partial examination of surviving documents and collateral evidence. Since it is now believed that the earliest draft to Master predates her friendship with Bowles, he cannot have been the person. On balance, Charles Wadsworth and possibly Gould remain the most likely candidates."

Hmm. I sense the approach of Valentine's Day. From now on, I would like to be referred to as "the Poet formerly known as George".