Hey I thought I was on the right track with my ideas here, but I was reading over this quote by Garland and now I'm confused again. Take a look
Garland talking to Zidane in Memoria:
"That is a picture of Gaia being assimilated by Terra. Five thousand years ago, Terra, alrady an old planet, sought to assimilate Gaia. Terra needed to merge with a younger planet to survive. However, there was already life on Gaia. And so, the story began... Life on Terra was coming to an end... We had no choice but to proceed with the fusion, which tragically destroyed Terra's native civilisations. Terra was too old to assimilate everything. Thus, I created the Iifa Tree to regulate the flow of souls back to Terra"
Say what, regulate the flow of souls back to Terra? 0_o?? I thought the Gaian souls were discarded as mist and Terra's souls were going into Gaia's cycle? What does all this mean here? I feel this game contradicts itself sometimes