Where did the saying carrying a torch as relating to romance originate?

Found on and clipped from: http://www.mtannoyances.com/?p=776: The following comes to us via the Word Detective: Since at least 1927, "to carry the torch" (or "carry a torch" for someone) has meant to continue to love and pine for someone long after the object of affection has left the building and any reasonable hope of amorous success has passed. By 1934, romantic ballads of lost love and broken hearts were known as "torch songs," and female nightclub singers who made them their specialty were known as "torch singers."

Much earlier, in 1775, we have this reference to the burning torch in the Epilogue to Irish playwright Richard Brinsley Sheridan's comedy The Rivals [citation]: In female breasts did sense and merit rule,

The lover's mind would ask no other school;

Shamed into sense, the scholars of our eyes,

Our beaux from gallantry would soon be wise;

Would gladly light, their homage to improve,

The lamp of knowledge at the torch of love! According to the Minnesota Jobs (?!) Web site, the idiom carry a torch may have a political etymology, at least in part: During the 19th century, a dedicated follower showed support for a political candidate by carrying a torch in an evening campaign parade. Only enthusiastic followers took part in such rallies. A fellow who carried a torch didn't care who knew that he was wholeheartedly behind his candidate. Later, the term was applied to someone publicly (and obsessively) in love. We shall conclude this consideration of carrying one's torch by consulting the good ol' Oxford English Dictionary, my premier reference source. In the entry for torch (n.), we have to carry a torch for defined in 1b as "to feel (especially unrequited) love for, to feel lingering affection for." The 1775 Sheridan reference is given as the first published instance of this particular figurative usage of carry a torch.