The life and work of Alfons Hoppenbrouwers (1930-2001), member of the Congregation of the Brothers of the Christian Schools, is characterized by great social and pedagogical engagement, coupled with an artistic and culture-based vision. In addition to being an architect, teacher and co-founder of the Sint-Lukas archive, he was also a visual artist. Out of his interest in Gestalt psychology, baroque music and architecture, Hoppenbrouwers developed geometric work in which he investigated how abstract oppositions - figure versus background - and cognitive arrangements of complex mathematical calculations generate form and arrange colour in the flat plane of plastic spatiality.

Harmonische reeksen presents a selection of geometric-abstract paintings in which musical compositions are converted into a mathematical-based visual language.

Hoppenbrouwers' work is based on architecture, number ratios and sequences, matrices and the music of Bach and Ockeghem. His oeuvre consists almost entirely of square paintings made with acrylic paint on fibreboard. Hoppenbrouwers painted juxtaposed colour surfaces without visible brushstrokes and shunned any form of formal hierarchy. Both the acrylic paint on the fibreboard and his use of colour create an illusion of transparency, entirely blurring the appearance of foreground and background. As a starting point for his work, Hoppenbrouwers set up a system of proportions and color-coding from which the final painting is developed.