The recent spate of poems and songs about birds, and blackbirds in particular, had me thinking about the way I find myself responding to certain poems and songs. Case in point: both Bye Bye Blackbird and the Beatles' Blackbird. Among the definitions of bittersweet, M-W includes: pleasant but including or marked by elements of suffering or regret. That's how these two songs make me feel. I get the same effect from Danny Boy. I wonder what other songs evoke similar feelings in listeners.