What does the expression “a drop in the bucket” (or ocean) mean and Where does it originate?

The expression “a drop in the bucket” means: Any quantity far too small; a smithereen.

The metaphor first appeared in the English translation of the Bible by John Wyclif (1382) in Isaiah ix, 15: “Lo! Jentiles as a drope of a boket, and as moment of a balaunce ben holden.”

In the King James version the passage reads: “Behold, the nations are as a drop of a bucket, and are counted as the small dust of the balance.”

Charles Dickens gave impetus to the further alteration or expansion in A Christmas Carol (1844).

In the first conversation between Scrooge and the ghost of his deceased partner, Marley, the ghost says: “The dealings of my trade were but a drop of water in the comprehensive ocean of my business.”

And nowadays the “drop” may be of any liquid into any proportionately great body.