Like a lot of poems, this one shares its title with the very first line. At first, you might just say that was some lazy title-making on Wordsworth's part. He puts all this effort into seven stanzas and he can't even come up with one puny title?
We feel you, Shmoopers, but, as first line titles go, we think this one is pretty appropriate. It essentially summarizes everything to come in the poem itself. "Strange fits of passion have I known" is pretty simple in terms of its content, really. It's all about… a strange fit of passion that the speaker experiences ("knows") during a trip to his beloved's cottage. Simple, right?
Well, let's not move on quite so quickly. This first line title gives us a few words that we think are worth a closer look. Let's take "fits," for example. A fit is really just a moment of losing control, but it's interesting that this word is plural. Clearly this is not the first, or last, time that that speaker's had an experience where a random thought has popped into his mind to ruin his mood.
That may be because the word "fits" is tied to the word "passion." There must be something about being in love—feeling passion—that gives our speaker these fits in the first place. At first that seems totally wrong. After all, being in love is supposed to set your mind at ease, to send all your cares drifting away into a bright blue sky filled with chirping birds. Right?
Think about it: is love really always good times and high-fives? If you're in love, doesn't that mean that—somehow, some way—you could lose love? That possibility sure seems like something to worry about. The anxiety that might naturally go along with being in love, then, goes a long way toward explaining our speaker's passion-induced "fit" in this poem. In that way, it's really not so strange after all.