We've got a bonafide world traveler on our hands in this poem, folks, a veritable tourist. Okay, so maybe world traveler is a bit of stretch, but the speaker of "The Solitary Reaper" definitely likes to go different places. He's an Englishman, and yet here he is in the Scottish Highlands. In the early 1800s, that wasn't the easiest place to visit. Remember, there were no airplanes, no trains, no bullet trains, no subways, no cars—no motorized transport of any kind. Our speaker definitely has the spirit of adventure, that's for sure.
He also knows when to keep his mouth shut. He sees this woman singing a really pretty song while she's working, and he quietly observes her. He doesn't want to disturb her because, well, that would be like standing up and shouting right in the middle of a movie theater. Our speaker has a sensitive, artistic side, and he knows when a performance is fantastic enough to be respected. He makes sure we know it too, which is why he tells his readers to be quiet and listen or to pass her "gently" (the highland lass is not to be disturbed). Come to think of it, this makes him sound almost like a museum guide or something, the kind of dude who says, "And here we have a highland lass. Be quiet while she sings, folks, or else you'll scare her off and then we'll have no more music."
In a lot of ways, the speaker of this poem really is William Wordsworth. Yes, technically, the speaker and the poet aren't the same person, but in this case we can make a small exception. Why? Well, we know that Wordsworth took a tour of Scotland in 1803 with his sister Dorothy and their good friend Samuel Taylor Coleridge. Wordsworth was also notorious for making notes of moments like the one described in "The Solitary Reaper" (it's the kind of thing Wordsworth really loved to focus on). If anybody had a knack for stumbling upon normal, everyday occurrences (a highland woman singing a beautiful song while working, for example) that turned out to be amazing, it was Wordsworth, the ever-observant poet of everyday life.