How do Dunstan’s war experiences lead to an interest in hagiology?

Dunstan's war experience of being wounded and seeing the Madonna with Mary Dempster's face ignited his interest in saints,

It was thus my interest in medieval and Renaissance art—especially religious art—came about. The little Madonna was a bee in my bonnet; I wanted to see her again, and quite unreasonably (like a man I knew who lost a treasured walking-stick in the London Blitz and still looks hopefully in every curiosity shop in case it may turn up) I kept hoping to find her.