Models are used everywhere, in daily life, sciences, engineering, and thoughts. They represent, support, and enable our thinking, acting, reflecting, communication, and understanding. They are universal instruments. Reasoning through and by models is, however, different from those that we use in ‘exact’ sciences and is far less understood. The notion of model is becoming nowadays well-accepted. Reasoning through models is far less understood and a long lacuna. This keynote aims at closing this gap.