It has been suggested that this tale represents the winter solstice illumination of Newgrange, during which the sunbeam (the Dagda) enters the inner chamber (the womb of Boann) when the sun's path stands still. The word "solstice" (Irish "grianstad") means sun-standstill. The conception of Aengus may represent the 'rebirth' of the sun at the winter solstice, him taking over the Brú from an older god representing the growing sun taking over from the waning sun. This could mean that knowledge of the event survived for thousands of years before being recorded as a myth in the Middle Ages. John Carey, an expert on Irish mythology, says that the tales of Brú na Bóinne are the only Irish legends where a sacred site is linked with the control of time.