Despite being lost for hundreds of years, the Solfeggio frequencies used by these chants would finally be recovered in the 1970s. Today, as shown by Dr. Horowitz, the 528 Hz frequency, which is the third note in the original Solfeggio, is used to repair DNA. This would explain why the Latin word for miracle is “mira gestorum”? Remember that 528 Hz is Mi on the original scale.
There is also the possibility that the scale was to some extent lost, which would not be surprising given the time period they were developed: Guido d’Arezzo’s lifetime fell right in the middle of Western Europe’s Middle Ages.
His death also came during a period of great contention between the Western Christian Church, which we know today as the Roman Catholic Church, and the Eastern Church, which we in the West now call the Eastern Orthodox Church.
This led to the Great Schism of 1054, a separation that still exists to this day.
So, while the Eastern Church and the Eastern Roman, or Byzantine, Empire was very active in preserving Western artifacts during the Middle Ages, they would have had very little reason to preserve a music scale created by the Western Church, especially since the Eastern Church had their own scale at the time, one with 8-tones called the Oktoechos.
In short, it is not impossible that the Solfeggio was actually lost in history, like so many other documents of the time.
In fact, the historical records place the introduction and rise of the twelve-tone scale in the century just preceding what most historians consider the end of the Middle Ages.