Final answer:
The sentry's statement about uncertainty applies to Creon's overconfidence in his own authority, leading to his tragic downfall. Creon's failure to listen to wise counsel further exemplifies the dangers of being too sure without considering other perspectives.
Step-by-step explanation:
The sentry's statement that "a man should never be too sure of anything" applies to Creon in several ways throughout the narrative. Creon's certainty regarding his edicts and moral standing backfires, leading to tragic outcomes for himself and those around him. This notion becomes a central theme in Sophocles' play, as Creon's hubris, or excessive pride, blinds him to the wisdom of moderation and the warnings of others, ultimately resulting in his downfall.
Creon's inflexible adherence to his own law above all else is his undoing. His refusal to bury Polynices and his harsh punishment of Antigone for defying this edict are examples of his overconfidence in his own authority. He is too sure of his personal interpretation of justice and the state's need to display strength, which prevents him from considering the possibility that he could be wrong, leading him to make decisions that are neither fair nor virtuous.
Moreover, Creon's interactions with characters like Teiresias, who offers him wise counsel, display his resistance to advice and differing perspectives. His overconfidence blinds him to the consequences of his actions until it is too late, illustrating the sentry's point that absolute certainty can be dangerous and that one must be open to changing one's mind in the face of new evidence or persuasive arguments.