Sincerity occupies a commanding position across the depth-psychology corpus, yet its valence shifts decisively depending on the tradition in which it appears. In the Chinese classical sources — the I Ching commentaries of Wang Bi, Alfred Huang, and the Taoist readings of Liu Yiming — sincerity (cheng, and more specifically the hexagram Zhong Fu, ‘Innermost Sincerity’) is not merely a psychological virtue but an ontological condition: the alignment of inner substance with outer act that enables transformative influence on both persons and polities. Confucius, as mediated by Huang, explicitly links the most complete sincerity with the full development of human nature and cosmic participation. In the Stoic vein, Marcus Aurelius treats sincerity as a transparency that ought to be legible in the body itself — the face, the very presence — and denounces its performance as a deeper debasement than open vice. Auerbach’s reading of Montaigne locates sincerity as the methodological prerequisite of genuine self-portraiture; its excess, not its absence, is what critics reproach. Hadot notes that ancient philosophy’s demand for consistent moral self-work paradoxically creates the appearance of affectation, raising the perennial tension between sincerity and spontaneity. Across these registers, sincerity converges on a single deep concern: the integrity of inner life and outer expression, and the psychological and ethical catastrophe that follows from their dissociation.