1. Mi Yitencha Ke’ach Li:^[1]

B. How even today Shabbos is considered the seventh day:

Both in scripture as well as in the language of the world, Shabbos is referred to as the seventh  day. This is a bit strange, as although indeed the original first Shabbos was the seventh day of creation, many days have passed since then and today’s Shabbos is not the seventh day from creation. Rather, the explanation is that number 7 does not refer to the seventh day from creation but rather to the seventh day from the previous six days of the week that followed it. You see, each one of the six days of creation correspond to a different one of the six supernal characters and attributes of the world of Atzilus. For example, on the first day the light of kindness shined and on the second day the light of Gevura shined, and so on and so forth for each of the six days of creation. On the seventh day, G-d rested which means that all of the days and their corresponding attributes became elevated to their root and source above. This concept continues to apply weekly, in every single week after creation and hence it is found that even today the seven days of the week mirror the revelations and attributes of the original seven days of the week at the time of creation. Accordingly, it is understood why we call Shabbos the seventh day even today as even today all of the attributes that shine on each day of the week are elevated above on Shabbos.

C. Shabbos elevates the sparks that were refined during the six days of the week:

Throughout the six days of the week the six emotional attributes of the world of Atzilus descend below in order to refine the sparks that are found in the worlds of Biyah [i.e. Beriya, Yetzira, Assiya]. On Shabbos, these sparks are than elevated above together with the elevations of the lower worlds.

D. Likras Kalah corresponds to the Shabbos elevation:

In the famous hymn of Lecha Dodi we mention the words Likras Kalah, which literally means “coming towards the bride.” In truth, however, this is referring to something totally different. The term Kalah in this hymn is corresponding to the word Vayechulu found in the verse of Vayechulu Hashamayim that is written in Scripture and read on Shabbos before Kiddush. This word is rooted in the word ceasing or finishing, and refers to the elevation to a higher level above, such as we find in the term Kalsa Nafshi, my soul yearns to be elevated and expire. The reason that this is mentioned on Shabbos is because Shabbos is the day that is dedicated and designated for the soul and all of the spiritual worlds to become elevated above.

E. Koneh Shamayim Va’aretz – Hashem bought Shabbos:

Our sages state that there are five products that G-d has bought and acquired and one of them is the Shabbos. This concept is likewise mentioned in the blessing of Meiyn Sheva in which we conclude with the words “Koneh Shamayim Va’aretz.” What does this mean and how does Hashem acquire something when everything is already His? The explanation is as follows: When one purchases something he moves the item from the possession of one person and brings it to his own possession. This is what happens on Shabbos; Hashem moves all of the lower spiritual worlds including all of their sparks of divinity higher up to his possession, to His world of Atzilus.

[1] Torah Or p. 79b-80b