What would the people who lived in the the Nordic countries a thousand years ago have thought about a fiddle player who could summon an invisible orchestra that followed every pitch being played? They would certainly have attributed this to some kind of magic, probably named it Sei∂r since that word meant both magic, string and the act of magically tying something (like the cord of fate).

The ”Sei∂r” in this piece is technology instead of magic, and it’s based around a technology I have invented called Gestrument (gesture-instrument). This technology allows for performing music within predefined rules controlled by data of some sort. That data can be from a touch screen, a motion sensor or the controls inside of a video game, but here it is actually the sound of the viola that drives the virtual orchestra that is accompanying the soloist – as if it was tied to a string.

From Wikipedia:

Seiðr is believed to come from Proto-Germanic *saiðaz, cognate with Lithuanian saitas, ‘tie, tether’ and Proto-Celtic *soito- ‘sorcery’ (giving Welsh hud, Breton hud ‘magic’), all derived from Proto-Indo-European *soi-to- ‘string, rope’, ultimately from the Proto-Indo-European root *seH2i- ‘to bind’.^[3]

Related words in Old High German (see German Saite, used both in string instruments and in bows) and Old English refer to ‘cord, string,’ or ‘snare, cord, halter’ and there is a line in verse 15 of the skaldic poem Ragnarsdrápa that uses seiðr in that sense.^[4] However, it is not clear how this derivation relates to the practice of seiðr. It has been suggested that the use of a cord in attraction may be related to seiðr, where attraction is one element of the practice of seiðr magic described in Norse literature and with witchcraft in Scandinavian folklore.^[4] However, if seiðr involved “spinning charms”, that would explain the distaff, a tool used in spinning flax or sometimes wool, that appears to be associated with seiðr practice.^[4] In any case, the string relates to the “threads of fate”, that the Nornir spin, measure, and cut.

Old English terms cognate with seiðr are siden and sidsa, both of which are attested only in contexts that suggest that they were used by elves (ælfe); these seem likely to have meant something similar to seiðr.^[5] Among the Old English words for practitioners of magic are wicca (m.) or wicce (f.), the etymons of Modern English ‘witch‘.