Long long ago, in the time of the Romans, young people used to get together in mid February to find new girlfriends or boyfriends. They did this by putting all their names in a hat and drawing out two at a time.
It was great fun.
But the old folk disapproved of the whole thing so much that they thought up a new game to replace it.
In this game you put the names of saints into the hat, and then you had to try to live for the whole year like the saint whose name you'd pulled out of the hat.
For some reason this game never really caught on.
At last the old folk gave up trying to stop the young people finding girlfriends and boyfriends, and instead came up with a saint especially to help them do it. Actually they came up with two saints, but they were both called St Valentine and they might even have been the same person some of the time.
Then everyone was happy, especially the old folk, who all started greetings-card factories.
Valentine. This day is named by spoil-sports after two at least partly made-up saints.
Thing to do today: say it without flowers!