"A solitary laugh is often a laugh of superiority"

This quote by Graham Greene suggests that when somebody laughs alone, it is often a sign of superiority. This could mean that the individual is feeling remarkable to those around them, or that they are laughing at something that only they comprehend. It might also be a sign of superiority in the sense that the person is laughing at something that they discover entertaining, but that others may not. It could be a sign of supremacy in the sense that the person is making fun of something that they find funny, however that others may not. It might likewise be a sign of supremacy in the sense that the person is laughing at something that they discover amusing, however that others might not comprehend. In any case, it signifies supremacy when somebody laughs alone.