Life is a horizontal fall.

William Blake, Satan with Adam and Eve, 1808

Ah! gentle pair, ye little think how nigh 

Your change approaches, when all these delights 

Will vanish, and deliver ye to woe; 

More woe, the more your taste is now of joy 

Happy but for so happy ill secured 

Long to continue, and this high seat your Heaven 

Ill fenced for Heaven to keep out such a foe
- John Milton, Paradise Lost Book IV