The Rails I18n library transforms a YAML file into a data structure that is accessible via a dotted path call using the t() function.
t(\'one.two.three.four\
There is a Gem too keypath-ruby
gem 'key_path', :git => 'https://github.com/nickcharlton/keypath-ruby.git'
Looking at the code (and guessing a little about what t is), it looks like you can do this:
t
t.value_at_keypath('one.two.three.four')