Mencius：I am skillful in nourishing my great spirit. This is the passion-nature: it is exceedingly great, and exceedingly strong. being nourished by rectitude, and sustaining no injury, it fills up all between heaven and earth. this is the passion-nature: it is the mate and assistant of righteousness and reason. without it, man is in a state of starvation. it is produced by the accumulation of righteous deeds; it is not to be obtained by incidental acts of righteousness. if the mind does not feel complacency in the conduct, the nature becomes starved.