On your identity, your surroundings
Nietzsche says:
“He who fights with monsters might take care lest he also become a monster. And when you gaze long into an abyss the abyss also gazes into you. (Beyond Good and Evil, Aphorism 146)”
Wikipedia summarizes Beyond Good and Evil well, though I encourage both of us to deeply read the book itself:
In Beyond Good and Evil, Nietzsche accuses past philosophers of lacking critical sense and blindly accepting dogmatic premises in their consideration of morality. Specifically, he accuses them of founding grand metaphysical systems upon the faith that the good man is the opposite of the evil man, rather than just a different expression of the same basic impulses that find more direct expression in the evil man. The work moves into the realm "beyond good and evil" in the sense of leaving behind the traditional morality which Nietzsche subjects to a destructive critique in favour of what he regards as an affirmative approach that fearlessly confronts the perspectival nature of knowledge and the perilous condition of the modern individual.
Nietzsche’s words in the start of this essay remind me of Jay-Z’s citation of ‘a wise man’ in The Takeover:
A wise man told me don't argue with fools
Cause people from a distance can't tell who is who
Nietzsche and Jay-Z both have important, intersecting points that yield lessons for all of us:
We are influenced by those that we engage with.
It’s hard to disentangle ourselves from or preventing becoming like those who we confront.
Bystanders will lack the context you have and perceive you and your enemies similarly. Be wary of this.
These words of wisdom are another part of the proverbial elephant that would also tell us that we should closely watch who we make our five closest friends as they will shape who we become. Notably, while we are mindful of friends and company we keep, we don’t as closely monitor the rivals or enemies we choose, let alone the fools we argue with.
There are many other pop culture examples of this, from Batman to Billions.
Ultimately, if distilled, the takeaway is to choose your company wisely, and remain vigilant to ensure fighting evil or ignorance does not lead you down your own wayward path. Wise words from wise people.