Baseball is a game where a curve is an optical illusion, a screwball can be a pitch or a person, stealing is legal and you can spit anywhere you like except in the umpire's eye or on the ball.

Murray’s line is a comic inventory of baseball’s built-in paradoxes: what looks real (a “curve”) is partly perceptual trickery; words double as both technical jargon and moral judgment (“screwball” as pitch or person); and actions condemned elsewhere (“stealing,” spitting) are normalized—within strict, quirky limits—inside the ballpark. The humor underscores how sports create their own miniature legal and linguistic systems, where ordinary ethics and etiquette are suspended and replaced by rulebooks and tradition. The quote also celebrates baseball’s folkways: its blend of precision and superstition, civility and roughness, and the way its language turns the game into a self-contained culture.