Celtic or Chivalric-MatriarchalThe survival of pre-Christian sexual mores and warrior codes from matriarchal societies, be they Celtic, Germanic, or Pictish, among the aristocracy of Europe can account for the idea (fusion) of "courtly love".
Classical LatinThe classical Latin theory emphasises parallels between Ovid, especially his Amores and Ars amatoria, and the lyric of courtly love.