About three years ago I bought my second guitar, it was an acoustic one and went looking for songs I could learn. Harvest was one of the first I found.
It's about a man walking through his own death. He moves through a garden, sees wilted things, feels shadows behind him. The whole thing has the atmosphere of a grey afternoon that won't end.
The line that gets you is "mourner's lament, but it's me who's the martyr." He's been watching a funeral this whole time and then realizes it's his. He's not a witness. He's the subject.
What Åkerfeldt never tells you is how the guy feels about that. Could be acceptance. Could be detachment as someone already so removed from the living that he's watching himself from a distance. Could be something darker, like this was always where he was heading. The song doesn't resolve it. The orchard just goes quiet. And it stays heavy.