Bab 359: Vol5 Ch29: Reason

〖 A newborn spirit needs to consume thoughts to grow 〗

'Negary' recalled the information within the [Theory of Spirit Summoning Rituals] book, spirits were closely related to emotions and the majority of the Principles they became entangled with would also be related to emotions; and so, most spirits required nothing but thoughts and emotions to sustain themselves.

And the specific emotion 'Negary's' spirit needed was the will to evolve.

Any discontent towards the present and will to grow stronger would suffice to stimulate its growth.

Which resulted in the spirit's ability: Lord of Evolution, capable of unlocking the limit of a living being to make them enter a state of evolution. During the period of the unlocked limit, as long as they had enough energy, that living being would be able to infinitely evolve to fit its environment. 

This was extremely similar to the Gears of Impurity that Negary had created.