Thoureau wanted to poit to the fact that following traditions limits us and deprives us from developing our imgination. Thoreau, like other romantic authors, does not agree with tradition. He thinks it prevents people from finding true greatness and blocks their path to spirituality. "Castles in the air" are simply illusions by which people persuade themselves in something that is not true, in Thoureau's opinion.
The supply of coal was crucial to the industrial revolution because coal was cheap and affordable and also it was an excellent source of energy. Coal was the best energy source at the time of the industrial revolution and would allow for machines to be coal powered.
Russian leaders adopted the idea of strong, centralized control of the empire.
The answer is B a statue because a religious icon is something that represents the whole religion, not just a painting or scroll.
