Professor St. John could be expected to express many emotions, but Cather is silent about all of them. He could express grief for the early and tragic death of Tom Outland. He could express some regret concerning his daughter Rosamund's excessive spending on her new home. He could express loneliness for his wife's lack of understanding of his needs. She chides him for sharing his thoughts with a student, and she doesn't understand why he doesn't want to go to France.
Desire is creation, it is the magical element in that process.
The access to heaven is through desire. The Cloud of Unknowing confirms both Underhill's and Cather's premise. Despite his tragic experience, I do not feel sorry for him, but instead I am drawn to him as he grows and changes. Grief or anger do not even occur to him or to me. The spiritual goal or desire of Godfrey St. Peter is perhaps achieved in his solitary days at the beach when the family was in France.