From childhood's hour I have not been As others were—
"Alone" opens with a short and simple sentence.
Our speaker says that, ever since he was a child, he has not been as others were. This is just like saying "I've always marched to the beat of my own drummer."
We're with him, but what does he really mean? Did he dress differently? Did he wear strange clothes? Did he have a loud haircut?
Probably not—this bad boy was written in the 1800s after all, and most folks just didn't go around rocking mohawks.
At this point, we don't know exactly what the speaker means when he says he was different so we should keep cruising along and see if he sheds some light on this little puzzle.
[…] I have not seen As others saw—I could not bring My passions from a common spring—
Well, this is nice. The speaker starts to give us a little more detail here about how he was different from all the other kids he knew growing up.
He says he has "not seen/ as others saw" and could not bring his passions from a "common spring."
Okay, so basically he's saying that he saw the world in a totally different light than everybody else.
And he also says that he felt things differently, or, as he puts it: he couldn't bring his "passions" from a "common spring."
Now, he's not talking about that thing that pokes out of your couch cushion. He means one of those things they put on the labels of bottled water.
The speaker is using a metaphor, then, to convey the idea that his feelings, desires, etc. came from a different source than everybody else's. They all come from some common place, whereas his come from somewhere completely different.
Look at it like this: say that all of your friends think the chocolate cheesecake at Cheesecake Factory is just the best thing ever, but, well, you can't stand it. The chocolate cheesecake just gets them so excited, but you prefer the strawberry cheesecake any day.
It's sort of like that. Everybody the speaker knew as a child got excited about one thing, but something completely different floated his boat.
Now, speaking of this "spring," did you notice that it rhymes with "bring"? Did you also notice that "been" and "seen" sort of rhyme?
Well folks, these are called couplets—they're like little couples, or pairs. Two lines in a row that rhyme = one couplet.
To read more about other formal features of this poem, head over to "Form and Meter."