And he goes on with a second possible theory on the roots of the Halo Story.
My only other theory of Halo history, (which is not as sound) is that The Forerunner(s), created the Flood, sealed them inside Halo, and left symbols and information for the Covenant to find. That is, assuming that the Forerunner(s) knew of the Covenant's religious beliefs. The Covenant were meant to open the door, releasing the flood, as a test of either the Flood or Covenant's ability as a species. Seeing how destructive they were, the Forerunner(s) wished to destroy the Flood, as a precaution for possible disaster. The whole Covenant-Human war wasn't expected, and not part of the Forerunner plan. Although, when the Forerunner(s) indestructible, living, speaking, live video camera 343 Guilty Spark found the Master Chief, the Forerunner(s) chose him to be a prime subject for activating Halo. This is all, of course, under the rash assumption that the Forerunner(s) weren't really gone, just watching everything happen through Guilty Spark.