Authors:

To be human is to keep rattling the bars of the cage of existence, hollering, 'What's it for?'

Robert Fulghum (2004). “All I Really Need to Know I Learned in Kindergarten: Uncommon Thoughts on Common Things”, p.261, Ballantine Books
To be human is to keep rattling the bars of the cage of existence, hollering, 'What's it for?'