To the Romans, this day was called Dies Mercurii, or “Mercury’s day” Mercury was a popular character in the Roman pantheon. A messenger of the gods, he presided over commerce, trade, and anything that required skill or dexterity. The Celts also worshiped Mercury and eventually equated him with the Norse god Odin (some spelling variations on this name include Wotan, Wodin, and Wodan). In Norse mythologies, Odin, like Mercury, is associated with poetry and music. Interestingly enough, both Odin and Mercury were regarded as psychopomps, or the leaders of souls, in their individual mythologies.
Odin, one of the main gods in Norse mythology, was constantly seeking wisdom. He traveled the world in disguise as a one-eyed man with a long gray beard, wearing an old, beat-up hat and carrying a staff or a spear (which brings to my mind images of Gandalf from The Lord of the Rings). In the Old English language, this day of Mercury evolved into Wodnes daeg, “Woden’s day,” or Wednesday.
Wednesday carries all of the planetary and magickal energies and associations of the witty and nimble god Mercury himself. Some of these mercurial traits included good communication skills, cleverness, intelligence, creativity, business sense, writing, artistic talent, trickiness, and thievery. And don’t forget all of those wise and enigmatic qualities associated with the Norse god Odin/Wodin, not to mention the goddess Athena’s contributions of music, the arts, handmade crafts, and writing. Wednesdays afford excellent opportunities for seeking wisdom, changing your circumstances, and improving your skills, be they in trade and commerce, music and art, or in communication and writing.
–Book of Witchery: Spells, Charms & Correspondences for Every Day of the Week