Semantically, `private` affects method definitions below it, so it's nice to have the method defs indented below them.  However, I find the rails convention to be ugly:

``` ruby
class Foo
  def public_method
  end

  private

    def private_method
    end
end
```

We like putting `private` at the same indentation level as the class to be the best of both worlds: it keeps all method defs at the same level of indentation, while visually showing that the methods below `private` are affected by it:

``` ruby
class Foo
  def public_method
  end

private

  def private_method
  end
end
```