This is the best bit I read today. Tip of the hat to T.C. for the pointer:
"...good fluency in a second or third language significantly expands one’s ability to see and understand and also articulate other points of view. And most of the very great thinkers of the past were fluent or semi-fluent in multiple languages. By teaching other languages at an early age, we can make our most productive thinkers deeper and more productive.