…to govern Zeir Anpin and Nukva through the power of Chochmah-Binah-Daat. For the specific intention here in Maturity is to bring Abba and Imma to complete rule over Zeir Anpin by providing him with his Chochmah-Binah-Daat.
They are then at full power… i.e. there is no further period of growth after Maturity: the periods of growth are completed at twenty years of age.
…and this is termed Neshamah. This is the end of the scale of the inner soul, the pnimiyut, as stated above.
Completion of Zeir Anpin during Pregnancy, Suckling and Maturity