"The Greeks bequeathed to us one of the most beautiful words in our language--the word 'enthusiasm'--en theos--a god within. The grandeur of human actions is measured by the inspiration from which they spring. Happy is he who bears a god within, and who obeys it."
...And who obeys it. That's the essential point. All too often we ignore our own "god within" and look for external validation to decide whether our passions are worth pursuing. I'm not saying that reality checks are useless and we should just let our freak flags fly. But I am saying that it's easy to come up with good (rational, pragmatic) reasons NOT to pursue our passions, and it's important to recognize what a precious gift enthusiasm truly is.
Louis Pasteur quoted in Kay Redfield Jamison's Exuberance: The Passion for Life, and found via Tom Peters (in the PowerPoint at the end of his post.)
