7-7-7 Today is the seventh week day on the seventh of the month of the seventh month of the seventh year of the new Millennium. This will not come round again until 8-8-8 so it is a very special occurrence. I wish you a happy seven day.

1. “To me, there are three things we all should do every day. We should do this every day of our lives. Number one is laugh. You should laugh every day. Number two is think. You should spend some time in thought. And number three is, you should have your emotions moved to tears, could be happiness or joy. But think about it. If you laugh, you think, and you cry, that's a full day. That's a heck of a day. You do that seven days a week, you're going to have something special.”
Jim Valvano

7 is a prime number. It is is the smallest positive integer requiring more than one syllable in English. 7 is considered the most mystical of all numbers because it is the one number from 1 to 9 which cannot be divided evenly into the circle. It gives a fraction ( 51.428571 ). The dividend from the division of the circle by the number seven is intriguingly close to the outer angle of the Great Pyramid: 51 degrees and 51 minutes.

2. “There are no seven wonders of the world in the eyes of a child. There are seven million.” (Walter Streitiff) . The seven wonders of the Ancient World is a widely-known list of seven remarkable manmade constructions of classical antiquity. It was based on guide-books popular among Hellenic sight-seers and only includes works located around the Mediterranean rim. Later lists include those for the Medieval World and the Modern World. Soon the results of the new seven womders of the world will be known.

3. The Seven Sisters of Sleep
Seven appears frequently in both eastern and western folktales. The Constellation of the Pleaides is called the Seven sisters. A Seven Sisters is also a type of pastry, with a custard-like bottom half. In Italian Football, the Seven Sisters refer to the seven largest clubs.

4. “Fall seven times and stand up eight.” (Japanese Proverb)

With very few exceptions, all mammals' necks have seven bones. There are seven openings into the human head (mouth, two eyes, two ears, two nostrils).

5. “We shall never understand one another until we reduce the language to seven words” (Kahlil Gibran). Patrick Ishmael said on his blog that "there are seven words you can never say on television... but which are said on the Internet. A lot".

6. “I busted a mirror and got seven years bad luck, but my lawyer thinks he can get me five.” (Stephen Wright, American Actor and Writer).
Long before mirrors were invented, people used to see their reflections in pools of water. Since they had no scientific knowledge then they believed this reflection to be their soul, or their other self. They also believed that any interference with the other self would injure it. So when mirrors were invented, and they were broken, it was thought that the other self was harmed. And where did this seven year thing come in? Well, the Roman belief was that life renewed itself every seven years. And, since a mirror meant “broken” health, it was believed that the person who broke it would need seven years to recover.

7. On the seventh hour, of the seventh day, of the seventh month, the seven doctors say: "He were born for good luck that you'll see". I got seven hundred dollars don't you mess with me 'cause i'm the hootchie cootchie man...

Muddy Waters' song "Hootchie Cootchie Man" - written by WIllie Dixon.
The reason for 7 being a lucky number symbolically is because it represents the union of man and woman, since the number for women is 4 and the number for men is 3.