The Protoss consider history to be of vital importance, and even during the Aeon of Strife scribes recorded the wars and their heroes for future reference. The Observatory is a modern refinement of the ancient library, where data gathered by Observers is recorded and cataloged.
Underwood, Peter, Bill Roper, Chris Metzen and Jeffrey Vaughn. StarCraft (Manual). Irvine, Calif.: Blizzard Entertainment, 1998.