Concepts are prime tools to describe a technical system, an organization and the products and processes of an industrial domain. Models and designs use a myriad of concepts - some of them quite complex. How to design concepts to describe artifacts like a clinic or a communications Network? How to conceive a complex artifact - its many aspects, characteristics, structures and functions? And if many concepts must fit together in one model like the pieces of a puzzle: How to design a tool kit of concepts? This story tells the quest for concepts.