The researchers found that while sadness is an extreme emotion, it is a wholly unviral one. Sadness, like what one might feel to see a stray dog shivering for warmth or a homeless man begging for money, is typically a low-arousal emotion. Sadness depresses our impulse for social sharing. It's why nobody wanted to share the Magnum photos but gladly shared the ones on the Huffington Post. The HuffPo photos were awe-some; they made us angry, or they surprised us. Such emotions trigger a desire to act--they are arousing--and that is exactly the reaction a publisher hopes to exploit.