I have not read any of the Forerunner Trilogy books but I would like to know, from information I've gathered from Halopedia and Halo Nation, this: why did the Forerunners meet the Flood and fight a war lasting three hundred years and not tell their civilization that an evil parasitic species was trying to consume all life in the galaxy, because, from the thirty pages of Cryptum I've read, the galaxy seems at peace.
I will not accept "They did not want to cause a panic" as a suitable answer. Use reasoning from the books, please.
[i may ask more questions about the Forerunner Trilogy as these books have left me confused about the massive changes to the backstory of Halo.]