What shakespeare meant by shoal of time in Macbeth?

The phrase "shoal of time" is used by Shakespeare in Macbeth to describe the fleeting nature of time. In the play, Macbeth is driven by his ambition to become king and commits heinous crimes in order to achieve his goal. However, he is ultimately defeated and killed, and his reign as king is short-lived. The "shoal of time" refers to the fact that Macbeth's time as king is like a shallow sandbar that quickly disappears, highlighting the transience of power and the futility of human ambition.

The phrase "shoal of time" is also used in the play to convey the sense of impending doom that surrounds Macbeth. As he becomes more and more consumed by his guilt and paranoia, he feels that time is slipping away from him and that he is being dragged into a whirlpool of destruction. The "shoal of time" becomes a metaphor for Macbeth's own mortality and the inevitability of his downfall.