What does the author mean about “exits and entrance “on man’s stage

What is the meaning of "full tide" as it is used in this sentence? before i could explain to her the differences of language in this world, she was embarked on the full tide of another subject. a long and involved argument an inaccurate representation a detailed and lively discussion an uncontrollable flood

Could someone me with this question?

How does tiresias prophecy affect the plot of the story ?