All of humanity's problems...

...stem from man's inability to sit quietly in a room alone.

- Blaise Pascal

The direct quote is, 

I have discovered that all the unhappiness of men arises from one single fact, that they cannot stay quietly in their own chamber.

- page 39, Pascal's Pensées, Published 1958 by E. P. Dutton & Co., Inc.

The original French, 

j'ay fouvent dit,que tout le mal-heur 
des hommes vient de ne fçavoir pas 
fe tenir en repos dans une chambre. 

- pg 203, Pensées de m. Pascal, Original French Manuscript, 1694