I think this is a perfect example of line as direction, under the assumption that direction leads you around the page. I suppose it would also be an excellent example of movement, but we have yet to cover that. ^_^ Anyways, here you have Hades, whose gaze and left arm lead you to Persephone. Her face guides you to her arm, which points you left, to Hades's right arm, which leads you back up to his head. Perfect composition!