A passage to India

What really happened in the Marabar caves? This is the mystery at the heart of E.M. Forster's 1924 novel, A Passage to India, the puzzle that sets in motion events highlighting an even larger question: Can an Englishman and an Indian be friends?
"It is impossible here," an Indian character tells his friend, Dr. Aziz, early in the novel.
"They come out intending to be gentlemen, and are told it will not do.... Why, I remember when Turton came out first. It was in another part of the Province. You fellows will not believe me, but I have driven with Turton in his carriage--Turton! Oh yes, we were once quite intimate. He has shown me his stamp collection.
"He would expect you to steal it now. Turton! But red-nosed boy will be far worse than Turton!
"I do not think so. They all become exactly the same, not worse, not better. I give any Englishman two years, be he Turton or Burton. It is only the difference of a letter. And I give any Englishwoman six months. All are exactly alike." ...