A second, more ancient riddle goes like this: "There are two sisters: one gives birth to the other and she, in turn, gives birth to the first. Who are the two sisters?" The answer is "day and night."
The real riddle is who built the Sphinx and when. The most compelling evidence suggests that the Sphinx was built for the Egyptian Pharaoh Khafre during his reign (2520-2494 BC), based on the architecture, geology, and archaeology of the Sphinx and its related monuments. But there are dissenting opinions on the matter.
One that tickles the imagination the greatest is based on the science of erosion. In the early 1990s researchers examined the distinctive pattern of rippling waves visible on the body of the Sphinx and the walls surrounding it. Although the body had been built using the different layers of limestone already there, the weathering appeared not to have been made by wind, but rather by water. And since the last Egyptian age to include substantial rainfall was over 7,000 years ago, history as we knew it needed a major overhaul. There are other ways to explain the erosion, eg, salt crystal exfoliation, wherein Nile salts sucked into the sand-covered Sphinx leached the limestone.
So the age of the Sphinx is somewhere between 5500 years and 7000 years. Either way, it's an incredibly old statue of totally unknown purpose. We're not even sure what the face used to look like, although there some early sketches that suggest features more typical of the Negroid race. Add to that, that the face may have been carved out of a larger head, which some have suggested was that of a lion.
We're also not sure what it was called. The commonly used name Sphinx was given to it in classical antiquity by reference to a Greek mythological beast with a lion's body, a woman's head and the wings of an eagle (although, like most Egyptian sphinxes, the Great Sphinx has a man's head and no wings). The English word sphinx comes from the ancient Greek Σφίγξ (transliterated: sphinx), apparently from the verb σφίγγω (transliterated: sphingo / English: to squeeze), after the Greek sphinx who strangled anyone who failed to answer her riddle.
Regardless of its age and purpose, the Sphinx remains a remarkable tribute to a civilization long gone from our collective memory. I wonder what might remain of our own civilization after 7000 years.