Before I start writing about the flute methods I own, a historical contextualization is necessary. The next three posts will be dedicated to the uses and the development of the transverse flute in the Middle Ages, the Renaissance, and the first century of the Baroque era - the moment in history in which the one-keyed flute begins to be largely employed. These posts will serve as basis to a better understanding of the sources I'm going to write about in the future.
The transverse flute in the Middle Ages
Custom dictates that the history of our modern flute starts in 1700 with the advent of the baroque flute and with the printing of the first pieces of music written for that instrument. Taking that point of view, the precedent centuries seem impenetrable and remote, especially those of the Middle Ages (5th to 15th centuries).
All the knowledge we possess concerning the medieval flute comes from a handful of images and some textual fragments from the Middle Ages. No extant medieval flute was found so far, so we are unable to know how they sounded like or how they were played. Added to that, just a fraction of the medieval music was written down - and what was written lacks information related to which instruments should be employed or how to play the music.
A miniature shown in a collection of songs published around 1340. The flautist holds her flute to the right, but only to harmonize better with the fiddle, making both instruments point to the image's central point. Most of the representations of flautists from the Middle Ages show the instrumentalists holding their instruments to the left and not to the right - like we can see above and like we do nowadays.
The interpretation of the written sources generates other kinds of problems. The word used to refer to the transverse flute applied, frequently, to recorders and whistle-like instruments. Besides that, looking for references of professional flute players in literature is a waste of time: at that time, musicians were not specialized in only one instrument, like most of us are today.
Many ancient images (many of them even more ancient than those of the Middle Ages) depicted flautists in mythological contexts. Greece, India, and Egypt have legends that associate the creation of the flute to deities: the Greeks with Pan, the Hindus with Krishna, and the Egyptians with Osiris. Among those legends, only the Greek legend of Pan belongs to the western mythological repertoire. However, Pan's flute was not a transverse one. Among those three cultures, Hindu culture was the only one to attribute the creation of a transverse flute to a god.
The transverse Hindu flute might have traveled to Byzantium around the 10th century and then it was spread into Europe. References to the transverse flute (both in visual arts and literature) start to pop out only in the 12th century. Until the 14th centurty, however, the use of the flute was limited to the borders of the Holy Roman Empire - which territory corresponds roughly to today's Germany. Due to that territorial limitation, the transverse flue became known as the "German flute" when it reached other countries between the 13th and the 14th centuries. The flute seemed to be already in use in France (where it was known as "flûte d'Allemagne") by the end of the 13th century. Paintings show that the instrument was present in French and German military music around the 14th century. In Spain, the flute was already known in the mid-fourteenth century, but the instrument would only be introduced to Italians in the following century.
The extant sources related to the transverse flute in the Middle Ages reveal that neither a consensus on how to build the flute or how to play it existed. The instrumentalists had to have a highly developed musical perception in order to be able to adapt the music they needed to play to the instrument they had in their hands at the moment. They should be able to, within a few minutes, identify where the tones and semitones of the flute were, identify the instrument's range, and play it accordingly. No fixed pitch existed for the flutes at that time - the pitch was different in each province, conditions under which every musical instrument was submitted to. Apparently, the only consensus was that the transverse flute should be held in a transverse fashion.
POWELL, Ardal. The Flute. New Heaven and London: Yale University Press, 2002.