I really love the lore, especially as it pertains to the Planescape setting. It's part of the Proclamation of Two Skies:

After the gith destroyed the illithid empire, Gith, a warrior-queen and leader of the rebellion, declared that the People would not rest until they had discovered and destroyed all remaining illithids in the multiverse; then, the People would be free to conquer all of the planes of existence and bring war to all other races. Many of the People’s hearts shared this goal. Zerthimon argued that the People already knew freedom and should begin to mend the damage done to their race. He too expressed a goal that was in the hearts of many of the People. Still, Gith insisted that hers was the only path and that they would be “under the same sky” in the matter.