The Sketch is a study in the field of a design theory which investigates drawing as a process of acting, thinking and recognition. It is presented here in the form of a book. The work, which was created as an MA thesis at the Basel College of Art and Design, views drawing not just as a an artistic experience for the development of an idea but rather as a thinking process which manifests itself as knowledge even in the production of images. The content of the study was developed in the to-and-fro process of drawing, thinking, researching and writing. The book which summarises the insights arrived at in this way is divided into three parts. The first deals with the processes involved in drawing, illustrating them with concrete examples. The second part is concerned with the analysis of a historical case study – the drawings of the nature researcher Maria Sibylla Merian. Finally the potential artistic practical application of these insights is evaluated and discussed.