Γελᾷ δ' ὁ μωρός, κἄν τι μὴ γέλοιον ᾖ → The fool laughs even when there's nothing to laugh at
unleugbar, evidens (augenscheinlich. einleuchtend). – haud od. non dubius (unzweifelhaft). – Adv. evidenter; haud dubie.