it is a white tower builded in the twilight isles , where evening sits for ever in the shade ; it glimmers like a spike of lonely pearl that mirrors beams forlorn and lights that fade ; and sea goes washing round the dark rock where it stands , and fairy boats go by to gloaming lands all piled and twinkling in the gloom with hoarded sparks of orient fire 5 1o ( *a northern venture : see i.204 , footnote .