Guidonian hand
In Medieval music, the Guidonian hand was a mnemonic device used to assist singers in learning to sight-sing. Some form of the device may have been used by Guido of Arezzo, a medieval music theorist who wrote a number of treatises, including one instructing singers in sightreading. The hand occurs in some manuscripts before Guido's time as a tool to find the semitone; it does not have the depicted form until the 12th century. Sigebertus Gemblacensis in 1105–10 did describe Guido using the joints of the hand to aid in teaching his hexachord. The Guidonian hand is closely linked with Guido's new ideas about how to learn music, including the use of hexachords, and the first known Western use of solfege.
Guido von List
According to the historian Nicholas Goodrick-Clarke, 1902 marked "a fundamental change in the character of [List's] ideas: occult ideas now entered his fantasy of the ancient Germanic faith." This began when he received an operation to remove a cataract from his eye, after which he was left blind for eleven months. During this period of rest and recuperation, he contemplated questions surrounding the origins of the German language and the use of runes. He subsequently produced a manuscript detailing what he deemed to be a proto-language of the Aryan race, in which he claimed that occult insight had enabled him to interpret the letters and sounds of both runes and emblems and glyphs found on ancient inscriptions. Terming it "a monumental pseudo-science", Goodrick-Clarke also noted that it constituted "the masterpiece of his occult-nationalist researches". List sent a copy to the Imperial Academy of Sciences in Vienna, but they declined to publish it. In 1903 List published an article in "Die Gnosis" magazine, which reflected a clear influence from the ideas of the Theosophical Society.