This is Jack, all Jack. Not only was he physical, but spiritual. How much was his mother influence was there in that action of taking Ennis's bloodied shirt, put it inside his own. Was it the shirts themselves or that Ennis's blood was on it. A physical part of Ennis. Was it the influence of going church with his mother, but not be able to tell Ennis what a Pentecost was, but remembering the hymn "Water Walking Jesus", but knew of faith, and of love, and worship of something greater than yourself. Jack was not a religious man but he was spiritual, the dozy embrace tells us that.
Every year he went to visit his parents how many times he held those shirts, and think of Ennis, and pray to him, to see him again, and finally reached out to him in his moment of despair, he seeks out Ennis and finds him.