Destiny. Fate. Karma. Words like these imply that the timeways are unassailable.
Would that were the case. To this day, many of Azeroth's inhabitants yearn to change the past. Yet just as our experiences shape us, they also shape the world around us.
Consider how those threads have woven the fabric of today's reality. Cut enough threads, and causation inevitably fails, unraveling that fabric. Indeed, cutting even a single thread short can result in disaster, provided it is the right thread.
This is the great burden of the Historian - should Azeroth's timeways come under attack, we must reconstruct history exactly as it happened, or the consequences could be dire. As we spread our stories and knowledge, so do we create a stronger future for us all.