Musubi

To tie means to be born.    "Musubi" is the Japanese word for "to tie". It derives from the term "musu" - to come into being and "hi" - spirit. Spirit in other words is soul. The soul that was tied and born then came to be called "Musuko" - son & "Musume" - daughter.
Musubi 結  is composed of two parts, the Kanji on the left part represents Thread and the one on the right represents Good Luck. Things are tied so that the soul inside cannot escape, so that it can not disappear before the knot is loosened.

The knot also reflects the relationships that are tied together, the word marriage "kekko結婚  in Japanese is composed from the kanji Musubi - Knot on the left and the kanji Relationship on the right. Two souls are tied together. 
To tie is something special. 
The Musubi is the heart of the Japanese craft Mizuhiki 水引 - an ancient Japanese art form that uses a special decorative cord to create traditional decoration, given away at Japanese occasions.
Mizuhiki embodies a range of significant cultural meanings. For example “Musubi-kiri” is a kind of knot that is very difficult to loosen once it has been tightly tied. Musubi-kiri signifies a wish for something to occur only once and not be repeated. It is often used for occasions which the individual does not want for them to happen again, including weddings and other celebratory events, as well as to offer one’s condolences.