In six days the world was created – the six days are the six emotions – the seventh day (malchus) receives from these emotions – though it is but a receiver nevertheless, as it is humble it contains everything.
Shabbos the receiver is the letter Zayin that has two heads – which represents both love and fear (the prerequisites for receiving.)
Now the six days of the week are “Divine emotions” – mainly love – however as God is infinite, no-one could handle (the infinite love) therefore every day is the restraining (constricting) of the love (in the specific vessel, so it can be absorbed.)
However as Shabbos is humble, it can contain the infinite.
This is why Shabbos both receives from the six days of the week, yet also blesses the six days.
This is why Shabbos can both inspire above, as well as give below.
From all the above we realize that the giver is called Vov and the receiver Zayin.
Now when you put a line bridging the top of Vov and Zayin you get Ches – and from Ches you get all effulgence – furthermore Ches represents the attachment of the Mikabel (receiver) to the Mashpia.
When Vov and Zayin (receiver and giver) attach, this makes Echad (1 – which is the combined number of 6+7=13)
In this unity, all light flows.
When the Jewish people (receiver) do the will of God (giver) this creates the Letter Ches from which all benefit come.
And within the Jewish people all the light pulsates.