Walking in wind and sun in the very landscape of liberty, he was still young enough to remember his politics and not merely try to forget them.
I want to make sure that "the very landscape of liberty" refers to the openness of the moors and commons he is walking in; or have I missed something?
For the second half of the sentence, I think it's all about the fact that young people make a big deal of their ideas and beliefs, thinking that they are what they believe in. Growing more experienced over the years, they start to notice the rupture between their ideologies and their reality, so they tend to "try to forget them" and focus more on who they really are.
Please, correct me if I get anything wrong, and thanks in advance.
For more context, here's a link to the story: http://www.classicreader.com/book/485/1