How many languages can fit into a brain?

I once had this substitute teacher when my English teacher was out on pregnancy leave. Now, this woman couldn't have been more than 5 feet tall, and she was at least 80 years old. She told us (attentive 6th graders who were still listening to teachers) about how she had survived the Holocaust in an Anne Frank-esque fashion, spending days cooped up in a closet.

Anyway, she was fluent in 13 languages. So, I don't know exactly how many are possible to learn, but it's at least 13.

Jam it back in, in the dark.