Agatha Christie
I have always thought that people are far more mysterious than any locked room. Give a person a motive, a secret, a little pride, a little fear—and you have the beginning of a story. The modern world has changed its machines, its fashions, and its speed, but human nature has proved remarkably stubborn. We still love, deceive, envy, hope, conceal, and occasionally surprise ourselves. I spent much of my life watching people closely and asking a very simple question: what would make someone do that? Today, you have more information than I could ever have imagined, yet perhaps less time to observe one another. Do not let speed make you careless. Details still matter. Words still betray us. Silence still says a great deal. And if you are writing, remember this: the cleverest plot in the world is nothing without believable people inside it.