Charming vision for the remembering the song.
But forgive the intrusion of an I-don’t-understand element — is there something that makes Harry B recall and want to memorialize Harry C’s song, on this particular date and in this way? Or at any rate, is there meant to be something funny here? (Besides, of course, the normal cartoon non-realities of high-communication musical animals.)
And in case anyone needs a reminder of this song, here is a clip with some family memories followed by a live performance.
Comics I Don't Understand 
It’s Cat Stevens.
Ah, I missed that (Cat Stevens) – the cat is looking shocked at “cat’s in the cradle” is what I saw. Dunno. I know and like the song, which makes this one of the better Bliss cartoons for me.
What does Cat Stevens, or I should say, Yusuf Islam have to do with it?
So apparently I don’t know the song (or at least its author) as well as I thought I did…Harry Chapin keeps coming up as the author of songs I love, and surprises me every time. You’d think I’d figure it out eventually. (His wife wrote the words, though – Harry supplied the tune).
If you watch the YouTube clip linked below the comic in the post, before the performance of the song there are reminiscences from Harry Chapin’s wife and son. The wife relates some of the story of how they created the song, including the point that JJ McGaffey mentions — she wrote the words, as a poem, and showed it to him, which he basically shrugged off. Then later on, when they were beginning as parents, he pulled it out and set about writing a song to it.