The fleur de lis is an ancient symbol. Some say it represents the Holy Trinity. But a more likely explanation is that it represents the three theological virtues of faith hope and charity. (This would also explain why there are three on the old royal standard of France for the Trinity, which otherwise would be redundant.) Just like the heart represents love, the fleur de lis represents virtue. As I said, it was on the old royal standard of France, representing the House of Bourbon. And as such, it is a de facto symbol of the French and French culture too.
i rather suspect it is of somewhat earlier origen then either concept. partially due to the aesthetics of the number three, as opposed to those of two or four. celtic dieties tended to be of tripple aspect, long before there was a christianity to come up with its trinity. of course it was in the renazaunce it attained its currently clasical form, but a motief of three interlinked spirals can be found in many celtic era carvings.
