Guidonian hand
Medieval mnemonic device assigning the solmization syllables to the joints of the fingers.
What it means
The Guidonian hand is a medieval mnemonic device for singing: the syllables and scale degrees of the tonal system are assigned to the joints and fingertips of the left hand. When the teacher points to a particular joint, the singer knows which degree and syllable is meant.
Musical use
The hand is attributed to Guido of Arezzo (about 990 to after 1033), who as a music theorist introduced the solmization syllables ut, re, mi, fa, sol, la and wanted to make sight-singing easier. The form of the hand we know probably arose only later, in the 12th century, and was used in teaching until the Renaissance. It arranges the notes from low G to high e² on the finger joints.
The Guidonian hand should be distinguished from today's Kodály hand signs, in which hand movements in space show scale degrees, and from notation itself, which it was meant to supplement. It was purely a teaching aid of singing instruction, not a notation system.
Performance practice
Try the idea on your own palm: assign scale degrees to the finger joints and point to the corresponding joint while singing. This links pitch, syllable, and spatial imagination, as medieval singers did.