Not sure what they mean by “intellectual vitality.” Would it be a good idea to write about my experience at the Stanford Model United Nations Conference - and what I learned about diplomacy, etc.?
Stanford question - "an idea or experience that has been important to your intellectual development"
If it inspired you to proceed studying this area, then yes, it’s certainly a great thing to write about. I wrote my essay about an online course from Stanford and about the way it inspired me to study machine learning.
I think intellectual vitality extends beyond simply an area you want to study and is more about the broad way you view the world.