Original: In Greek mythology, Zeus places his son born by a mortal woman, the infant Heracles, on Hera's breast while she is asleep so that the baby will drink her divine milk and will thus become immortal.
Simplified: In Greek mythology, Zeus places his son (the baby Heracles) whose mother was a mortal woman on Hera's breast while she is sleeping so that the baby will drink her divine milk and become immortal.