Mercurius" is a medieval Latin noun used to describe messengers, of which the Roman god Mercury is most famous. Eloquence and swiftness are characteristics attributed to these couriers and that is reflected in this piece. The forward motion of Mercurius is a constant in the bass part while the melody floats above, first in octaves, then as a duet, in a smooth flowing manner. The harmony is realized in conjunction with the rhythmic pattern of the bass to convey the purpose of this "bearer of news.