Why is this the answer?

The answer is hourglass because this super clever riddle is describing a special tool that people use to measure time! It is a beautiful object that tells a story about how fast time moves, even when everything else seems quiet and still. This puzzle is fun because it makes you think of an object having the parts of a person. Let us look at the first clue: "Two bodies have I, though both joined in one." When you look at an hourglass, you see two round glass containers, which are called bulbs. One is on the top, and one is on the bottom. These are the "two bodies." They are connected right in the middle by a very narrow opening, which is why the riddle says they are "joined in one." It is a neat design that allows the fine sand inside to flow freely from the top section to the bottom section, always marking the seconds and minutes as they pass. The sand must move from one "body" to the other to do its job. Now for the second part, which is the trickiest clue: "The more still I stand, the quicker I run." This is a clever word puzzle because it makes you think of a running race. The hourglass itself does not have legs and does not move or "run" around the room. It stays very still on a table or shelf. Instead, the thing that "runs" is the time it measures, which is shown by the quick flow of the sand. When you turn the hourglass over and set it down completely still on a flat surface, that is when its important work begins! The sand immediately starts to pour, or "run," through the tiny opening, and it marks a specific amount of time, like one minute or one hour. The more perfectly still and quiet the hourglass is, the faster the sand seems to rush through to the bottom. Once all the sand is in the bottom bulb, the measured time has "run out." It is a wonderful way to see time passing, all while the beautiful glass structure simply stands still.