An old sukkah - made for the festival

Beit Shammai invalidate an old sukkah and Beit Hillel validate it. An old sukkah is one made thirty days or more before the festival, not specifically for the festival. But if it was made for the festival, it is valid even if built at the start of the year. The Gemara explains that Beit Shammai learn from "make yourself the festival of Sukkot" that the sukkah must be made for the festival.

1. 1Restate the source in your own words.
2. 2Identify the central distinction and explain its significance.
3. 3Apply the distinction in the exercise without adding a ruling absent from the source.