I found a <a href="http://innig.net/software/ruby/closures-in-ruby.rb">script</a> that explains everything really well. Credit goes to:

Along with <a href="http://eli.thegreenplace.net/2006/04/18/understanding-ruby-blocks-procs-and-methods/">this blog entry</a>, it's made the whole deal much easier to figure out.

Now.. Why didn't I get that when I was looking at LISP?