The Painted Veil by William Somerset Maugham

She saw Waddington every day, for he strolled up the hill to the Fanes' bungalow when his day's work was done; and so after a week they had arrived at an intimacy which under other circumstances they could scarcely have achieved in a year. Once when Kitty told him she didn't know what she would do there without him he answered, laughing:

‘You see, you and I are the only people here who walk quite quietly and peaceably on solid ground. The nuns walk in heaven and your husband – in darkness.'