Why does a baby look into his mother's eyes while breastfeeding?

Preprogrammed: Babies seem to be preprogrammed to look at circular shapes like a mother's eye. They will also preferentially look at items like a dartboard that are shaped similarly. At that age, that is really all their brains are able to resolve (that is a whole 'nother post). It probably aids in bonding and certainly aids in visual development.

Because he likes to: Eye contact is how we make connections with other people. There are diff levels of eye contact, & also the babies proper level of eye focus is about the distance from mom's elbow 2 mom's face. We all want to love & be loved, & eye contact is one way for us to do that before we speak. If you are looking at the eyes you can't help then to look at the face, & a focus of nonverbal communication.