What is the significance of telling the wood to waken?
Malbim: This is a wondrous metaphor. The verse depicts the dead body of Belshatzar, which lies mute without Ru'ach Chayim, and it is dressed in gold and silver, like his idol. The idol made Belshatzar, who served it, to be like itself. He calls to the idol of wood and stone to wake from its sleep and hear his Tefilah.
Why does it say "Dumam"? "Even" is feminine!
Radak: This is a general term that applies to masculine and feminine, like Reikam. We find "Shvi Dumam" (Yeshayah 47:5).
Does the idol teach?!
Rashi: No ? this is said in astonishment.
Malbim: No ? Belshatzar teaches that my words were correct, that the maker will get from the image what the image got from him ? to be a mute idol dressed in gold and silver, without Ru'ach, for his Neshamah left.
How is it "Tafus Zahav va'Chesef"?
Radak: It is covered with gold and silver. It is not flesh and blood, which can receive Ru'ach ? it is silver and gold! Therefore, "v'Chol Ru'ach Ein b'Kirbo" ? even Ru'ach of an animal.
What is the meaning of "v'Chol Ru'ach Ein b'Kirbo"?
Radak: There is not any Ru'ach in it. This is like "Kol Melachah Lo Sa'asu" (Vayikra 23:3) ? any Melachah. "Kol Chelev v'Chol Dam" (ibid. 3:17) ? any Chelev or blood.
