But we used who for nearly everything. Who do you trust? Who do you love (the Rolling Stones, I think)? Who's next (The Who, of course)? Who's your favorite rock group? The Guess Who, of course.
Somewhere along the way, whom became popular. Everyone told us to use whom. Whom do you trust? I trust him, since whom and him are both objective, not subjective.
Nowadays, people use whom for everything. Well, not everything; Mick Jagger just wouldn't say "whom do you love?" I don't blame him.
I agree with most uses of the word whom -- for whom the bell tolls -- but I think it's overrated and overused. Who's overrated? He is. That's right.
When I was in college, my journalism teacher pointed out to us that there are times when who is correct because it's part of a phrase. Sadly, I can't give an example; it's been too long.
I guess I'm into civil disobedience, a subject that Henry David Thoreau would appreciate. Whom would live on Walden Pond? (Actually, it's who would know. You know?)
And whom would know for sure? No, who knew. Who wrote the letter? Yes, he did. Who's on first? That's right.
But who's on second? No, What's on second. And who's on third? No, Who's on first (apparently, his name is Don Who). But who's on third? I Don't Know.
Hey, that's right. I Don't Know is on third.
(Whom's next? Nah.)