Mid February was traditionally the time of the Lupercian
festival, an ode to the God of Fertility and a celebration of
sensual pleasure, a time to meet and court a prospective mate.
In AD 496, Pope Gelasius outlawed the pagan festival. But he was
clever to replace it with a similar celebration, although one
deemed morally suitable. He needed a "lovers" saint to replace
the pagan deity Lupercus.
The martyred Bishop Valentine was chosen as the patron saint of
the new festival.
Saint Valentine had been beheaded for helping young lovers marry
against the wishes of the mad emperor Claudius. Before
execution, Valentine himself had fallen in love with his
jailer's daughter. He signed his final note to her, "From Your
Valentine", a phrase that has lasted through the centuries.
Pope Gelasius didn't get everything he wanted. The pagan
festival died out, it is true, but he had further hoped people
would emulate the lives of saints. Instead they latched onto the
more romantic aspect of Saint Valentine's religious life. While
not immediately as popular as the more passionate pagan
festival, eventually the concept of celebrating true love became
known as Valentine's Day