Ok, heres my ToL/MoL theory. Mata Nui and Makuta for some reason put their spirits into masks(Mask of Light,Mask of Darkness) and then wait for a matoran to find them. Makuta is found first and his spirit is joined with the matoran, forming the Makuta we know now. He then puts the MoL in a rock so no one will find it. Much later Takua rolls the rock into lava and the MoL is reveled. Takua than puts it on and his spirit is fused with Mata Nui's, forming the Toa of Light!
Edit:Sorry about the double topic, my computer was messing up.