Metis was the Titaness of the forth day and the planet Mercury. She presided over all wisdom and knowledge. She was seduced by Zeus and became pregnant with Athena. Zeus became concerned over prophecies that her second child would replace Zeus. To avoid this Zeus ate her. It is said that she is the source for Zeus wisdom and that she still advises Zeus from his belly. It may seem odd for Metis to have been pregnant with Athena but, never mentioned as her mother. This is because the classic Greeks believed that children were generated solely from the fathers sperm. The women was thought to be nothing more than a vessel for the fetus to grow in. Since Metis was killed well before Athena's birth her role doesn't count.