There is an enormous difference in the power music has in this fifteenth century work and what it had when St. Guthlac was being attacked by the knobby-kneed demonic hordes in the 8th century. Henryson's music has power only insofar as it is intellectually correct. No amount of gemilling, however, can make Orpheus' emotionless, slow-working music the equal to the olifant, with its life and world-changing powers. By the time Henryson writes this poem, the greater part of music's power has disappeared, and it has begun to become what it is now: a form of entertainment. Perhaps it is not even a particularly engaging, judging from Orpheus' audiences' responses of fleeing or falling asleep. Nor is the need for the music as pressing as it is in Erec and Enide. Nature, in its wisdom, tries to convince Orpheus not to ply his musical trade to release his affection, Eurydice, from Hell. It tries to make him more content with his lot. Music has lost the deep power it had in the early Middle Ages, when it was an almost supernatural, magical force. By the time Henryson write Orpheus and Eurydice, music is controlled entirely by reason.
The way music is presented in these works mirrors some of the larger trends of the Middle Ages. By the end of the Middle Ages, music and its power are secularized. In Guthlac and Roland, the music is inexorably bound to God, and faith in God. In Erec and Enide the music is magical, if not Christian, and carries the promise of perhaps more power than it shows. By the time Sir Orfeo was written, music was still powerful, but its universal power had been lost. No longer did music create an aura around its performer. During his time as a hermit Orfeo was only powerful while he was playing. Music in Sir Orfeo and Orpheus and Eurydice was also secular. In the romance of Sir Orfeo, almost nothing is said about God, and there is certainly no indication that Orfeo's music is a God-given gift bestowed to permit Orfeo to protect himself or further God's plan.
Music becomes less universal across the scope of these works. On the battlefield at Rencesvals, the fate of thousands, if not the fate of whole nations, rests upon a decision about whether or not to blow the horn. In Orpheus and Eurydice, almost nothing rests upon the music. Indeed, the goals attempted through song are not achieved, and the implication is that perhaps the goals were not worth achieving. Nothing is changed from the beginning of the story to the end, except that Orpheus becomes a better musician by becoming more intellectually astute. There is the transition from the epic mindset where, as Chrysostom says, the wrong sort of music has the power to "overthrow everything" (Chrysostom 68) to the romances of Sir Orfeo, where at best music can earn the right to a gift, and there is no counterbalancing evil music.
In these tales music makes a transition from magical to rational. For Guthlac, the psalms pit God's magic against the magic of the devil, and in nearly every case win. In Roland, the strange ability of the olifant to communicate so much and so clearly to Charlemagne, as well as the olifant's mortal wound to Roland, exceed the possibilities of reality. In Erec and Enide, the magical horn is the guardian and key to a magical garden. By the time Sir Orfeo is written, however, the magical powers of music are becoming more limited - only nature responds in an unexpected way, and even that response is extremely limited. In Orpheus and Eurydice, all the power music has is related to its rationality and near-scientific status. Nature does not respond at all to Orpheus' music, it responds to the grieving musician. Similarly, the guardians of Hell are moved by the Thracian king's harping only because he has mastered the understanding of modes. Music still has power but it does not come from magic.
In much medieval literature, as in medieval history, most power still comes from the warrior whose sword is unbreakable and whose valor is unquestioned. Even in the perpetual warfare of the Middle Ages, however, there were ways of gaining power that do not revolve around violence, spiritual influence, or even money. Music could control demons, events, magic, and those who listened to it, and so doing could give the musician a degree of power. The warrior, too, used his trumpet to change the world around him, an act which is certainly powerful. It is important that in reading medieval literature, listening to medieval music and viewing medieval art, the role of the music in those creations not be dismissed as merely decorative. The power of music is present in these works, and cannot be dismissed.