Herbert Spencer, I think, defined Progress as the advance from the simple to the complex. It is one of the four or five worst definitions in the world, both regarding impersonal truth and also personal application. Progress, in the only sense useful to sensible people, merely means human success. It is obvious that human success is rather an advance from the complex to the simple. Every mathematician solving a problem wants to leave it less complex than he found it. Every colonist trying to turn a jungle into a farm fights, axe in hand, against the complexity of the jungle. Every judge is summoned to expound the law, because a quarrel is complex, and needs to be made simple. I do not say it always is made simple, but that is the idea. Every doctor is called in to remove something which he himself frequently calls a “complication.” A really able doctor generally sees before him something that he himself does not understand. But a really able doctor generally leaves behind him something that everybody can understand — health. The true technical genius has triumphed when he has made himself unnecessary. It is only the quack who makes himself indispensable.
[…]
It is the attraction of the detective, and the reason of the real drag of romantic curiosity in all detective stories, that while he begins with a thing so hot and confused as crime, he is yet trying to end with a thing so cold and obvious as law. Those, like myself, who have hunted for good detective stories as dipsomaniacs hunt for drink, know that this is the real difference between the readable and the unreadable tale. The bad mystery-story is that which grows more and more mysterious. The good mystery-story is that which is mysterious, but grows less and less so. A footprint, a strange flower, a cipher telegram, and a smashed top-hat — these do not excite us because they are disconnected, but because the author is under an implied contract to connect them. It is not the inexplicable that thrills us; it is the explanation we have not heard. It is the thing we call art, the thing we call progress. It is the advance from the complex to the simple.
— The Illustrated London News, 30 November 1912.