"Alone" is one of those poems that never really had a title. But wait, we just said it's called "Alone." So…yeah, we should probably clarify that. It has a title now, but young Edgar never bothered to give the poem a title while he was still alive (remember, it remained unpublished at his death). When the poem was finally published in 1875, the publishers decided to give it the oh-so-apt title "Alone."
Apt? Yes, we said it. For starters, "Alone" is a poem about, well, loneliness. The whole first half of the poem is about all the ways in which the speaker is different from all his peers. He sees things differently, he feels sorry about different things, his passions come from elsewhere, and so on. The speaker's complete difference from everybody else makes him feel—you guessed it—alone. As he says, "all I loved, I loved alone" (8).
There is another sense in which the title "alone" is apt. Think of like this: you can say "I am sitting by myself in my room eating candy, and I am all alone." You can also say, "I alone, among my friends, can speak Chinese." It is a small, but important difference. The speaker is both alone, as in lonely, but alone as in the only one who is special.
Okay, so the poem doesn't actually say that, but think about that line "I loved alone." If you push just a tiny bit, you can see that it can be read both ways. It means both "I loved by myself" and "I alone loved." The underlying idea is this: the speaker is alone, but his loneliness is also uniqueness. So this one-word title is full of hidden complexity—a bit like our speaker.