Desire displays the pinnacle of Thielen's artistic vision. Thielen worked no less than seven years on this polyptych which, unlike the other polyptychs, widens as the shutters are opened. The work symbolizes human desire in all its facets. The first side of the work thereby depicts the yearning infatuation and sexual desire of the initial attraction between the desired and the desiring.

The second side, twice as wide as the first side, shows the pain of unfulfilled desire. This desire can be interpreted both as love desire and man's desire to possess things outside himself.

The crucified man in the painting symbolizes man's powerless suffering, trapped in his desire. The city, at the bottom right of the work, also symbolizes the human urges subjected to desire. In contrast, the female model represents pristine nature. She does not desire, but is free. The bed on which she sits is perpendicular to the cross to which the man is chained and symbolizes free intimacy.

The third side of Desire shows the fulfillment of desire, which takes place both in the arts and in the family. Central again is the bed, a symbol of the free subconsciousness into which the arts are born and a symbol of the fulfillment of desire. The images around the bed are dream fragments, connected by the use of the theme of "indirect light." On the far right is depicted the artist's family, which represents the material fulfillment of desire.