In order to maintain their personality and complete the "reincarnation," the Sages erased their memories.
An ordinary brain could not possibly bear the vast memory and the various abilities far exceeding those of humans that they possessed. In order to awaken the other self inside Nico Ross and access the extremely complex stacked memories, Nico Ross would have to continue growing, constantly improving in every aspect, until finally reaching a certain level of ability--only then would the final step of resurrection be possible.
These two factions were jokingly referred to as the 'Lie-down-and-win' faction and the 'Struggle' faction, who constantly debated each other, with neither side able to convince the other.
The 'Lie-down-and-win' faction tended to believe more in fate, or perhaps were more superstitious about the arrangement of the Sages, viewing Harrison Clark as a true god rather than a human being.
