It says here that it is probable that the valentine was the first of all greeting cards.
6598 seconds sound clip from the Be My Valentine, Charlie Brown movie soundboard.
You can hear this line at 00:03:05.069 in the DVD version of the movie.
Quote context
[...]
- This is a privilege and an honor.
- I could die from all this honor.
- I think I could spend my whole life here and still never get a valentine.
- It says here that it is probable that the valentine was the first of all greeting cards.
- Originally, Valentine's Day was set aside as a lovers' festival.
- Oh, Schroeder, isn't that romantic? A lovers' festival.
- Sometimes I think you don't realize that you could lose me.
- Are you sure you want to suffer the tortures of a memory of a lost love?
[...]