"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"

This quote by C. S. Lewis is a commentary on the complexity of human nature. He is recommending that our impulses are in conflict with one another, and that if we listen to each one, it will attempt to persuade us to prioritize its own requirements over the needs of the other impulses. This resembles how people can have various opinions and beliefs, and every one will attempt to persuade us to prioritize their own viewpoint over the others. Lewis is suggesting that it is challenging to comply with all of our instincts, just as it is tough to follow all people. He is stressing the complexity of humanity and the problem of making decisions that please all of our requirements.