<Dd> 13 . When made public love rarely endures . </Dd> <Dd> 14 . The easy attainment of love makes it of little value; difficulty of attainment makes it prized . </Dd> <Dd> 20 . A man in love is always apprehensive . </Dd> <Dd> 30 . A true lover is constantly and without intermission possessed by the thought of his beloved . </Dd>

When was the art of courtly love written