The Art of Painting can be seen as Thielen's first full-fledged polyptych. In this autoreflective work, the then 26-year-old artist posed an artistic manifesto on painting itself.

On the one hand, the work shows his sources of inspiration on the closed side of the polyptych. The artist's partner at the time is depicted as the muse. Below that, the artist's parents are depicted and at the very bottom, on the panel that is also referred to in art history as the "predella", the process of the making itself is painted.

On the other hand, the polyptych shows a different artistic genre on each panel, thereby acting as an exhibition of the diversity of the artist's talent. The closed side shows the portrait, self-portrait and still life. The opened side adds the landscape and the depiction of the clothed and undressed model and the mannequin.

This work was part of the traveling exhibition "Around a polyptych" (1983), in which the work traveled through several museums in the Netherlands.