Rabbi Shimon fled to the cave to escape a death sentence for publicly criticizing Roman culture. According to folk tradition, during his twelve years of isolation, he engaged in mystical meditation and wrote the Zohar, the central work of Kabbalah.
The sukkah is a symbol of fragility. We build the temporary structure each year and know that it is only meant to last for the week-long holiday. It sways in the breeze. The raindrops land inside. The animals nibble at our decor. We know it could come crashing down on us.