The problem with the concept of "courtly .love" is that it is more a product of the scholarship of the late 19th and 20th centuries than a term actually used in the Middle Ages themselves. In general, it describes a phenomenon in which there an idealized longing for a beloved that inspired the lover to perform great deeds. One of the reasons that one type of courtly love was not supposed to be between spouses is that its nature had to do with its being impossible to consummate and thus not physical in nature, while the purpose of marriage was primarily the production of children. Some types of courtly love were similar to the concept of love found in Plato's Symposium, which is spiritual in nature and also echoes or parallels the allegorical readings of the Song of Songs that were common in medieval Biblical interpretation. Other variations were more Ovidian, linked to revival of aristocratic and courtly culture, had a stronger sensual component, and aimed towards consummation.