I recently completed a leadership program at my corporation and they had a similar first pillar of knowing thyself. This always makes me think of the prevalence of Mirror Bosses at the end of video games. The greatest enemy to concur is one's self.
This is the same taxonomy they taught in my college (a military academy). Freshmen learned to lead (what we called 'manage') themselves,sophomores to lead 1-2 freshmen, juniors small teams,and seniors organizations (100+ students).
In hindsight, I can't imagine a better way to build one's self into a leader.