“Burning the midnight oil” means staying up late to work, study, or finish a task. One of the earliest reliably documented appearances of its central image is in Francis Quarles’s 1635 book Emblemes, which uses the words “midnight oyle.” That is an early record, not proof that Quarles invented the expression: people may have used similar language before it appeared in print, and the exact modern wording developed over time.
The image belongs to a world lit after dark by flame. Oil lamps were one source of light, though candles were also common, and neither offered the ease or brightness of modern electric lighting. A person working late might literally need to keep a lamp supplied with fuel. Quarles’s phrase connects that practical detail with the effort of laboring while others sleep, a connection that made the image easy to understand.
A popular retelling presents the saying as a direct description of scholars burning oil in lamps through the night, as if a single historic practice gave birth to the idiom. The literal picture is plausible, but the evidence does not establish one particular worker, occupation, or event as its source. Nor should Quarles’s early use be treated as a confirmed coinage. His wording shows that the association between late-night effort and lamp oil was already available to readers in the 17th century; it cannot tell us exactly when or where the expression began.
Over the centuries, the phrase shifted from the physical fuel used to keep a flame alight toward the work itself. Today, no lamp is required: “Maya burned the midnight oil to finish her presentation” simply means she worked late, while “We’ve been burning the midnight oil to prepare for the opening” describes an extended stretch of effort. The phrase endures because its vivid old-fashioned image still makes a familiar experience—working long after dark—feel instantly recognizable.