he is not the kind whose shield wounds others

Self-belief at 19 is a proposition altogether different than self-belief at 25, just as optimism at 11 is a proposition altogether different than optimism at pimple-laden, broken-voiced 15. Maybe it's the case that the same words at different intervals of time are like the same species incarnated in different individual instances: this "justice" differs from that "justice" like the lion who licks his chops in the Serengeti differs from the lion who sits in a concrete enclosure, licking his balls and waiting for another piece of meat to be slid down the chute. So but maybe the operative term here is concepts, not words: a single concept deployed in a given context is an instantiation of the general class to which it belongs, but whose specific properties both abide by and diverge from that class so as to belong in different degrees. Just think of individuals you know who bastardize a familiar concept like love or goodness or accountability, or who embody it so thoroughly and uncompromisingly that your understanding of what the idea could possibly be dilates in this person's wake. Goodness gracious me, it's complicated.