Two great minds to admire. 

Richard Feynman talks about the beauty of a flower. This man had a fire in him for knowledge, something we should all aspire to create within ourselves, if only to see just how great and wonderful our world truly is. 

Carl Sagan talks about the great library of Alexandria and its loss to human civilization. Again, Carl had a wonderful ability to inspire others by simply talking about grand concepts with humility and passion.