The universe is like a safe to which there is a combination. But the combination is locked up in the safe.

— Peter De Vries

Supernova remanent in Cygnus

Supernova remanent in Cygnus

Central section of the veil nebula. One hour exposure.
The Veil  is a supernova remanent. It exploded some fifty thousand years ago. The filaments are a shock wave that is expanding in a dusty region, clearing it as it goes. Notice that many faint stars are visible at the bottom where the dust has been cleared than at the top.