Mercury's Day in Practice

Wednesday carries Mercury's significations: mind, communication, travel, negotiation and commerce, following the qualities classical astrology assigns the planet closest to the Sun and fastest moving after the Moon. Older astrological and magical handbooks recommend Wednesday for correspondence, contracts, study, short journeys and any undertaking whose success depends on clear thinking and effective exchange of information rather than on emotional appeal or sheer force.

Mercury was read as neutral rather than benefic or malefic in its own right, taking on the character of whatever planet it was aspected by in a given chart, and Wednesday inherited something of that adaptability in practical use: it was considered a flexible day, suited to intellectual and mercantile activity generally rather than to any single narrow purpose, in contrast to the more specifically weighted characters of Tuesday's Mars or Friday's Venus.

Sources A History of Western AstrologyNicholas Campion with Grimoires: A History of Magic BooksOwen Davies