Why is the construction of the Mishkan juxtaposed with Shabbat (Shemot 35)?

When G-D created the world He unleashed His unlimited power to create all forms of existence-inanimate, vegetable, animal, and human beings.

G-D however, purposefully performed His task in an incomplete manner. The last word of the story of creation is LA'ASOT (to do) (Bereshit 2). By using this word, G-D asks that we complete creation and in partnership with Him redeem the world.

Perhaps the greatest manifestation of human creativity in the Torah is the building of the Mishkan. This construction required human mastery over every aspect of creation. For example, gold was required to construct the Menorah, the Golden Altar and the Holy Ark. Copper was required for the Copper Altar and the Wash Basin. Herbs and vegetables were used for the dye needed to color parts of the Mishkan and the clothing of the Kohanim. Animal skin was used to cover the Mishkan, and human interaction was essential to coordinate a building venture of this great magnitude.

Nechama Leibowitz points out that the same words describing G-D's completion of creation; "VAYICHAL VAYAR and VAYIVARECH" are also used to describe the completion of the Mishkan.

In the course of becoming so successful, human beings are in danger of forgetting that G-D is the Source of all our creativity. Therefore, the laws of Shabbat restrict us from activities that indicate our mastery over the world. By observing Shabbat, we assert the centrality of G-D in all of our endeavors.

The first 11 of the 39 categories of prohibited work on Shabbat deal with activities of agriculture, leading up to the baking prohibition. The next 23 MELACHOT deal with animal life, leading up to sewing and writing. And the next 4 MELACHOT deal with the building process.

In withdrawing from each of these actions, we acknowledge G-D as the Supreme Master over the entire universe.

The final category of MELACHA is the prohibition against carrying. This leads to the understanding the even in the social sphere, carrying is a symbol of human interaction, G-D is also in total control.

Thus the juxtaposition of Shabbat to the Mishkan is to teach that even the Mishkan could not be built on the Shabbat. This is a reminder that G-D alone is THE only Source of all existence.