In short, the Middle Ages was the thousand year period that began with the fall of the Roman Empire in the fifth century. During these times, sacred song (Gregorian chant) began to develop and flourish in the Western Christian Church. These chants are considered to be great historical treasures of the Western civilization because they allow us to clearly see and study the religious faith and values of the time.
The most popular and important element of the religious practices was the daily Mass, which many of us are somewhat familiar with. Around the thirteenth century the purpose of this liturgy, or the sacred texts performed in the services, was to glorify God, teach the Gospel of Christ, and exhort and inspire the worshippers to continue along the paths of righteousness. There was no room for secular music in the churches at this time in order to remain true to this purpose (although as the centuries passed, secular songs in worship services eventually became more and more commonplace. The composers would integrate the melodies of their more famous pieces into their sacred compositions in order to attract a greater audience to the churches and to gain more popularity. Interesting, right!? But that's another story.)
Before the Introit or introductory section of the Mass, there was often a Liturgical Drama performed to precede the more formal service. In these dramas, different scripture stories and passages were read and acted out through characters. They were like little religious musicals. :)Anyways, all the different characters would sing their dialogues to each other except for one. Whenever a drama was performed with the Devil as a character, he was not allowed to sing his part. Instead, he could only speak. It was so interesting to listen to an excerpt of one of these particular dramas, for you'd hear the hauntingly beautiful Gregorian chant being performed phrase by phrase by the other characters. Then right after the strains of their melodies faded, a man's voice would deliver his lines in a creepy shout/moan. The contrast between the song and the speech was striking when the entire piece was listened to.
Also, the very buildings that Mass was celebrated in were designed to evoke awe and grip not only the mind but also the heart. The high ceilings and murals of the churches and cathedrals were meant to draw the eye heavenward. The architecture was meant to accompany the music in its purpose of edifying the worshippers. Now within these resonant cathedrals, the spoken word was often lost; however, singing carried the words clearly to all corners of the building. To a populace that was mostly illiterate, these musical services were their main sources of religious instruction.
The fact that Satan cannot sing is symbolic of his separation from God. Music represented the divine, and singing was like a connection and a prayer to Heaven. Learning about this not only showed me how significant sacred music is, but it also taught me once again about godly attributes. If we personally develop righteous talents and qualities, we can become closer to God. God has given us the opportunity to do so because we are his children. He wants us to return to Him.
"For my soul delighteth in the song of the heart; yea, the song of the righteous is a prayer unto me." (Doctrine and Covenants 25:12)
"Praise ye the Lord. Sing unto the Lord a new song, and his praise in the congregation of the saints." (Psalms 149:1)
"Behold, God is my salvation; I will trust, and not be afraid; for the Lord Jehovah is my strength and my song; he also has become my salvation." (2 Nephi 22:2)
"The Lord is my strength and my shield; my heart trusted in him, and I am helped: therefore my heart greatly rejoiceth; and with my song will I praise him." (Psalms 28:7)