The English language is filled with idiomatic expressions, or phrases that seem to have one meaning but actually convey a figurative meaning. "Carry the day" is one such idiom. "Carry the day" does not infer the impossible lifting of a 24-hour period of time, but to win a battle or victory or to cause to be successful. For example: "After many successive defeats, the soldiers believed that their general's new plan would carry the day."
It is estimated that there are more than 25,000 idiomatic sayings in the English language, not counting the minor, regional idioms that abound across the English-speaking world. The meanings of idioms might easily confuse and frustrate a student of the English language. A student who rises at the crack of dawn each day to put on his or her thinking cap might only end up eating his hat after laboring over the highways and byways of baffling English idioms such as these.
The saying "carry the day" is no doubt derived from the Latin "victoriam reportare," meaning "to carry off the honors of the day," according to Brewer's Dictionary of Phrase and Fable. Certainly the Romans were familiar with victory, and it is no surprise that the phrase should infiltrate the English language, an amalgam of German and Latin roots with numerous dialects and regional varieties. Not limited to describing victory in war, the phrase "carry the day" might also be compared to an inspirational figure or act of heroism or as a superlative of one object or great work over another.
The use of "carry the day" in classic literature is scant, because the idiom is more commonly used in vernacular as slang. The phrase is used in Charles Dickens' preface to his masterpiece David Copperfield, in which Andrew Lang from the 1917 Harvard Classics Shelf of Fiction reprint of the book compares the novel with another Dickens' classic, The Pickwick Papers. Dickens also utilized the phrase in his book A Tale of Two Cities, but the reference seems to be more literal — "carry the day's wine" — than figurative.