succos

The Posuk says כי בסוכות הושבתי את בני ישראל בהוציאי אותם מארץ מצרים; the reason we sit in the succah is because 'ה housed us in succahs on the way out of mitzrayim. Rashi says that the succahs we're referring to are the ענני הכבוד
We all know the famous question.
If we're commemorating going out of mitzrayim, why don't we have succos in nissan, when we left mitzrayim? The חידושי הרי"ם gives an interesting answer. He says that the mitzva is למען ידעו; that we should know what happened. The mitzvah of succah requires knowledge. Throughout most of the year people have many sins, and we know that a person doesn't sin unless a רוח שטות comes over him. So throughout the year we're considered lacking the knowledge to perform the mitzvah of succah properly, but after rosh hashana & yom kippur, when we're free from sin, we have the דעת to perform the mitzva of succah in the ultimate fashion.
Asks רבי אליהו גוטמאכר, normally, by mitzvos we say that they don't need kavana. However, by succah we see that this mitzvah requires special kavana. Why over here do we need to know the reason for the mitzva?
The אלשיך says over the following mashal.
The רמב"ם, as we know, was a great doctor who divided his time between the palace of the king as his private physician, & his home, where he studied the Torah. When he would go from his house to the palace, all the sick people would line up along the way and he would instruct them on a remedy to cure their sicknesses.
One day as he was going, there was a man standing with all the sick people, who was obviously healthy. The רמב"ם asked him, why are you standing here with the sick people ? The man told him, I'm a teacher of small children, and recently another rebbi moved into town & took my livelihood away; I was hoping you could help me. The רמב"ם said, I'm sorry to hear that, but I'm a doctor; I help sick people. The man told him, you help people to eat & sleep. I can't eat or sleep - I need your help. I can't eat for I have no money, & I can't sleep because I worry about my family. The רמב"ם said, if that's so, then you too should be cured of what ails you, and told him to take one melon, and make sure to take care of it so that it will last a long time. Time went on & nothing happened. The man was discouraged but still cared for the melon.
Winter comes, & the king gets sick. The רמב"ם is summoned and concludes that the only cure is a ripe melon that was ready to be pulled from the ground in the summer. They searched the land to no avail. The schoolteacher hears about this & brings the melon that he's been caring for, to the king. When the king is completely healed he makes a big party & gets up and asks the man to name his reward. The man is so excited! Finally, he can get what he's been wanting. He says, please king, let there be no one else allowed to teach children in this town except me. The king says, that I can't give you for it's my day of happiness. On my day of celebration I won't do anything that would be harmful to anyone.
The man leaves dejected. The next day when the רמב"ם leaves his house to go to the king, the dejected schoolteacher is on the line again with the sick people. The רמב"ם asks him, why are you here again? The man tells him what happened at the king's party. The רמב"ם says, you fool! Why wouldn't you ask him for 100,000 gold coins which he would have gladly given you & you wouldn't have to teach again?
The אלשיך says, we learn from here that if a person has a request to ask of someone, you have to pick the right time. If it's a time of joy & happiness, then ask for something good. If you need to ask for something that even though it might be good for you, is bad for others, wait until it's a time of anger, then ask for what you need. Based on this, says רבי אליהו גוטמאכר , the days of succos, when we're commemorating the עני הכבוד that 'ה made to protect us from all harm, is the time that's most opportune for us to ask 'ה to protect & lookout for us for the whole year. That's why we need to know the reason for the succah, so that we know what we could be asking for. Just like 'הprotected us then, he will protect us throughout the generations. All we have to do is ask at the most opportune time, when we're free from sin. Now is when 'ה is בשמחה, so we merit the ultimate protection!