It means that items and ideas, even nature itself dosen't change are perception of it does. A forest can be nice to look at in the daylight then at night all alone it become scary to you. As for a picture you could do a gun where its used by a cop and a criminal.Or a group of people listing to a concert some will like it some will hate it but the music is the same. Perception is reality, and perception can change.
"Go confidently in the direction if your dreams. Live the life you imagined."
The true meaning of life is found only through one's happiness. Life can have over a million meanings this way, but happiness is the key to your personal answer. By choosing the path that you want to take a walk down in life, you you're choosing the one that will make you happy. For instance, Thoreau had a lifestyle lived relatively in the forest. It's what made him happy. Through this, he enjoyed living since he had went down the path that he chose causing him to live the life he imagined.
"Disobedience is the true foundation of liberty; the obedient must be slaves."
Every country has its own sense of liberty. The United States for instance is considered 'the land of the free, and the home of the brave.' If that's true, then why does our country have rules? In the past, slaves had a life full of hard work. They had to be obedient or suffer a beating. In today's society, you have your choice to be free. You have to follow the law. The choice of liberty is the choice that makes you happy even if it means going against law. Staying within the limits that your friends, parents, or even Obama puts you in just makes you another puppet of society. Choice is freedom. Even if that choice is to disobey.