There are many different stories describing the origin of Valentine's Day.
One of the most accepted stories has Valentine as a Bishop in the early Christian days. The early days of Christianity were dangerous times, since Christians were still looked at as a threat to the existing governments.
Valentine was accused of helping other Christians escape death and as result he was seized and dragged through the streets of Rome to appear before the Prefect. He was thrown into jail, where his spirits and faith never waned.
The jail keeper had a daughter who was blind. The story says that the jail keeper taunted Valentine by saying "Your God can't even cure a young girls blindness".
Valentine refused to be discouraged, but instead prayed to God for a miracle, to restore the young girl's sight and help the non-believers believe.
Through the intercession of Valentine, the girl's daughter was cured.
The emperor was not impressed with the miracle, but rather panicked at the thought that people might hear of this and turn to Christianity and away from him. So he ordered that Valentine be beheaded.
The morning he was scheduled to be executed, legend has it that Valentine sent the jail keeper's daughter a farewell message, one she was now able to read.
The message read simply "From your Valentine."