In Part Two, Chapter Four, Gabriel receives three letters. What do the letters say and who are they from?

In Part Two, Chapter Four, Gabriel receives three letters. In the letter from his mother, Gabriel learns that his brother Felix is rejected for military service due to his poor eyesight and Major Cobb refuses to speak to Felix. In the letter from Felix, Gabriel learns that Felix's schoolmate Holland is also rejected, so the two will attend Oxford together. Gabriel finds he is unable to read the letter from Charis because it makes him miss her too intensely.