G‑d called upon both heaven and earth to bear witness to the message He was about to deliver to the Jewish people.
Heaven on Earth
הַאֲזִינוּ הַשָּׁמַיִם . . . וְתִשְׁמַע הָאָרֶץ וגו':
(דברים לב:א)
[G‑d said,] “Listen, O heaven . . . Hear, O earth.”
Deuteronomy 32:1
G‑d addressed both heaven and earth in order to teach us that we are called upon to harmonize the two. The Torah originates in heaven and consists of G‑d’s vision for the perfection of the world. By spreading the knowledge of the Torah to ourselves and to others, we are bringing heaven down to earth. By reshaping both our own lives and the lives of others in accordance with the Torah’s teachings, we are bringing life on earth up to heaven. When we have made life into “heaven on earth” – reconciling the division between the two – heaven and earth testify how we have fulfilled our mission in life.1
But why? Without being told the point, what motivation is there? Is it merely to make the world a footstool for Gd? If so, surely he can create ine of his own that will be infinitely superior to anything we can do. And if the world becomes like heaven, what is the point in the real heaven after we die?
The cornerstone of Chassidic teachings is based on the Medrash that G-d wanted to have a home in this world see - chabad.org/257034 for a full treatment of this. As far as after we die, we are taught the ultimate reward, known as The World to Come (Olam Haba) will take place with the resurrection of the dead in our physical world, and it will be greater and more pleasurable than anything we experience in Heaven - the section What Comes After Heaven? for a short piece about this. For a more in-depth treatment of this please see The World to Come: Why a Bodily Resurrection? from the book To Live and Live Again.