To answer these questions, we must first understand the concept of sukka. Mefarshim explain that it reminds us that our existence in this world is only temporary. As we say in Shacharis on Shabbos morning, "The days of our life are seventy or eighty years, full of toil and distress, only to be abruptly severed as we are taken away." On Musaf of Rosh Hashana we declare, "The life-span of man is likened to a fleeting shadow, a passing cloud, a puff of wind, and a momentary dream." This isn't meant as an insult, but rather to energise us to focus on the true goal of the Eternal World.

This thought is the root of attaining happiness. The society we live in preaches that material wealth and enjoying a good life brings happiness. However, a sophisticated look at the world around us indicates that this isn't all that true. We see how much stress and hardship people undergo to achieve and maintain success. And as much as we have, we could always use just a bit more. A man once saw Baron Rothschild stooping to pick up a lost coin in the street. Astonished, he asked the tycoon why he bothered to pick it up. The Baron replied, "For the same reason anyone else does. Money is money."

So if wealth doesn't yield happiness, what does? In Pirkei Avos (4:1) we learn Eizehu ashir hasameach b'chelko - Who is wealthy? One who is happy with his lot." When we understand that this world is fleeting, our needs and worries fall into proper perspective and we are freed of their yoke. True joy is the release from the rat race, letting go of chasing the pot of gold at the end of the rainbow. As a wise man once said, "What we perceive as the real world is really ethereal; what we call the spiritual world is in fact substantial and solid."

There's a famous story with the Chofetz Chaim, who was once asked by a visitor why he had such dilapidated furniture. The Chofetz Chaim responded, "Where's your furniture?" "Why I'm only visiting here!" "I too", said the sage wisely, "am only visiting here." In a similar incident, a young man with many troubles went to speak with Rav Shmuel Auerbach shlita, son of Rav Shlomo Zalman Auerbach zt''l, and a world famous sage in his own right. Rav Shmuel sighed at hearing the person's difficulties, and his sigh conveyed the depth of his sorrow at his own life's misfortunes: having no children, living inextreme poverty, being recently widowed. They sat silently together for a while, until Rav Shmuel comforted his visitor, telling him, "Isn't that what this world is all about? Mir mutchit zich ap apar yahr un nochdem gait men tzurik tzum Bashefer - We suffer a few years and then return into the hands of the A-lmighty."

It's said of Shlomo Hamelech, wisest of all men, that he had a tablet before him on which it was inscribed, "gam zeh yavor - this too shall pass." When his kingdom prospered and he feared falling prey to arrogance, he glanced at these words and was reminded that wealth is only temporal. When troubles befell him, he once again looked at the tablet and was comforted that his troubles would be resolved.

This is the message of the sukka. By relocating into a hut, we are conveying the idea that this world is transient, diras aray, and this brings in its wake joy, Zman Simchaseinu. Rav Moshe Feinstein zt"l cites stories of people who were informed by their doctor that they were terminally ill and had only a few months left to live. How they cherished each precious moment, spending their time in the wisest way possible instead of wasting it on foolishness. Sukka drives home the message that this world is temporary and we should concentrate on what's truly meaningful.

Accordingly, Sukkos is during the fall, when the harvest is brought from the fields into the silos. In an agricultural based society, where most people are farmers, this is the season of joy with one's abundance and wealth. By moving into a sukka, he releases himself from the shackles of mundane affairs, to soar free as a spiritual being. Thus a sukka must be erected under the open sky, for when inside the sukka one has no barriers between himself and Hashem.

The concept of the arba minim, writes Sefer Hachinuch (mitzva 324), parallels this. By taking the four Species and waving them before Hashem, we dedicate all our success and achievements to Him. Our joy at the harvest is channelled towards an outpouring of affection and commitment to Hashem. Also, the arba minim are shaped like different parts of the human body: the esrog is patterned like the heart, the lulav resembles the spine, the hadas leaves are formed like the eyes and the aravos leaves simulate the lips. This signifies that every facet of our physical being is inducted into the service of Hashem. Consequently, the two mitzvos of Sukkos are directly related to the same theme.

Therefore, Koheles is read on Shabbos Chol Hamoed of Sukkos for Koheles describes the insignificance and brevity of the pleasures and vanities of this world. As we assert in the Psalm recited in a house of mourning, "Fear not when a man grows rich and increases the splendour of his home; upon his death he will not take anything, his wealth will not accompany him." There is yet another Scripturally mandated mitzva of Succos that was performed in days of yore: Nisuch hamayim, the drawing of water and pouring it upon the Altar. This was done amid tremendous rejoicing, so much so that we are taught that whoever missed seeing this spectacle, has never seen a joyous occasion in his life! The prophet Yonah was elevated to the status of prophecy through this experience of joy as we learn, shemesham shoavim ruach hakodesh. What is the significance of this mitzva and why was it performed with such joy? Water is the most basic need of mankind. On Sukkos, we take our most fundamental need and place it in the Divine service. Our commitment to Hashem is total; nothing is left outside the worship of Hashem. This is the source of inner happiness: the total release from physical endeavours.

Interestingly, Sukkos concludes the three Regalim and the Yomim Noraim. Pesach celebrates our physical liberation from bondage, Shavuos our spiritual eminence by receiving the Torah, and Sukkos is the culmination when we are totally elevated from the mundane. The Yomim Noraim accomplish the same thing by atoning our sins and setting us free from the chains of our Evil Inclination. Therefore, Sukkos is simultaneously the finishing point for both the Chagim and the Yomim Noraim.