Why seven blessing?
is associated with forming something new. The end of creation is introduced with the words “Vayechulu hashamayim veha’aretz, vechol tzeva’am… And they were completed — the heavens, the earth, and all that live in them…” The word “vayechulu” (they were completed) shares a root with “kallah”, bride. The wedding is the completion of the creation of the individuals entering the marriage. Note that these blessings are said for a week, at the wedding and at each meal for the first week the couple is married at which there is a minyan (quorum of 10) attending and new people present to celebrate the wedding. Saying seven blessings for a week brings up the 7×7 motif. This is a common motif in Judaism. Some examples: The seven blessings for seven days of sheva berachot. The seven weeks of counting omer between Passover (the physical redemption of Israel) and Shavout (the revelation at Sinai). The seven sabbatical cycles — each seven years — leading up to the jubilee.
