What does the holiday of Sukkot have to do with letting go of our need to control outcomes? First of all, before we get to that, what is Sukkot anyway? Like many Jewish holidays, it combines historical, spiritual and agricultural elements. It's the holiday where we build these temporary structures, called sukkahs, or booths, and when we shake the lulav (a willow branch, a myrtle branch and a palm branch all tied together) with the etrog (a large lemony fruit).
Fundamentally, as we decorate the sukkah with fruits and vegetables, we are celebrating the harvest. In fact, sukkahs are thought to be reminiscent of the temporary structures farmers would inhabit while living in the fields during the harvest season. It may well explain why one guideline determining whether or not a sukkah is kosher is how close to the ground the walls come. The rule is that the gap between the ground and the bottom of the walls cannot be more than the width of a goat crawling on its belly. That makes a lot of sense if the goal of a sukkah was to protect you while sleeping outside during the harvest when you would not want to be disturbed at night by a wandering animal.
Another determinant of whether or not a sukkah is kosher is that you must be able to see the sky from within the structure. In other words, living in the sukkah should feel a lot like living outside, i.e. feeling like you're a part of nature. Here, perhaps, we come to the crux of the matter.
When Jews shake the lulav, we are actually doing a rain dance, and why do a ceremony praying for rain even while we're bringing in the harvest? Because we're all neurotic and already worrying about the next harvest as we're bringing the current one in. If it doesn't rain, there will be no food, and we won't survive without food.
Interestingly, it's not coincidental that Sukkot comes RIGHT AFTER Rosh HaShanah and Yom Kippur. Here's why. During the ten Days of Awe from Rosh HaShanah to Yom Kippur we are instructed to "get clean" with people by asking for and granting forgiveness. Once we've done this and have essentially purified ourselves, then it's time to pray for rain, the really important culminating act that helps ensure our survival.
Judaism teaches that we can and should do our best to purify our souls, that this can help lead to a better outcome, but that ultimately it's out of our hands. We purify ourselves; then we pray for rain. We understand, though, that whether or not it rains is beyond our control, but we pray for it anyway, and we recognize our limitations in determining what will happen.
The history of humanity it seems is the attempt to control outcomes, to deal with our fear of survival and satisfy our sometimes greed-filled need to insure a better situation for ourselves. We generally fail to recognize that even as we try to control more and more, and propagate the illusion that we can, we are still and forever will be subject to the random vagaries of life and the universe. Oh well. Maybe that's why the ceiling of the sukkah has to be partially open to the sky, to remind us that we are vulnerable beings, and even though we would like to dominate the natural world, it has a funny way of asserting its control over us.