Telling us to obey instinct is like telling us to obey 'people.' People say different things: so do instincts. Our instincts are at war... Each instinct, if you listen to it, will claim to be gratified at the expense of the rest.
The C. S. Lewis Signature Classics (8-Volume Box Set): An Anthology of 8 C. S. Lewis Titles: Mere Christianity, The Screwtape Letters, Miracles, The ... The Abolition of Man, and The Four Loves