Cause and effect. When you see a clock, a car, a house, you see a intelligent effect. Some humans manipulated some matter in a intelligent way and constructed those things I wrote. The objects: car, house, clock, etc, are effect from an intelligent agent: man, the cause who in fact is an co-creator. The primary creator, cause of all other things, including matter manipulated by human, human, animals, etc, it's an intelligent being. An intelligent effect must have an intelligent cause. That's all, very simple.