A signature always reveals a man's character — and sometimes even his name.

Esar’s quip plays on the idea—popular in the early-to-mid 20th century—that handwriting and signatures can disclose personality (the premise behind graphology). The first clause treats a signature as a compressed self-portrait: a habitual mark that may betray temperament, vanity, haste, or care. The punchline reverses expectations: beyond “character,” a signature is also supposed to reveal the literal name, yet in practice many signatures are illegible scrawls. The humor depends on that everyday frustration while also hinting at a broader skepticism toward claims that outward marks reliably disclose inner truth.