Warring authoritarians on opposing sides are near-identical mirror images.

Evidence

Such people, with their fear and their self-righteousness, tend to drive and perpetuate the conflict between groups. But if you are in the front rank on one side, glaring at your hated enemy in the first rank across the way, you are really looking at a mirror. He is you. — Bob Altemeyer, The Authoritarian Specter, 1678

Categorization

• CANDY: ‘You are really looking at a mirror. He is you.’ is a punchy aphoristic line.
• SEED: Could be an essay angle: the psychology behind why enemies with identical pathologies hate each other most.