a candle is not a fundamental unit of measure but a candela is! I guess you must have skipped school a few times too then. Candela is the unit of measure of luminous intensity for a source of light. A candle has a luminous intensity of approx. 1 candela. A lumen is the unit of measure of a luminous flux. To be a little more clear, it's the intensity of light in a cone of a specific angle (from 0 to 4pi, 4pi being a sphere).