an ant trying to topple a giant tree -- ridiculously overrating one's own strength; a person's overestimating his strength; an ant trying to shake a big tree; ants attempt to shake a tree; try to sweep back the Atlantic with a broom:
A tiny insect, trying to shake a mighty tree, is ludicrously ignorant of its own weakness.; like ants trying to shake a huge tree, ridiculously overrating themselves; They were merely like ants trying to shake a giant tree. How they overrated themselves!