This is the "Saint Bavo is received by Saints Amand and Floribert" painted in 1611-12 by Peter Paul Rubens. As a preliminary sketch, it was intended for St Bavo's Cathedral in Ghent, but it's an oil on wood painting that shows incredible detail and colour.
Here we see Saint Bavo being welcomed to the monastery by Saints Amand and Floribert. He's a former Roman soldier who renounced his life as a warrior to become a monk. The scene is set outside St Peter's Church in Ghent, where the cleric hands him a black habit to replace his armour.
Notice how Rubens has used bright colours to highlight Saint Bavo, contrasting with the more muted tones of the background figures. The use of short and rapid brushstrokes creates a sense of movement and energy in this hectic scene. Some of these oil sketches by Rubens were even used as finished works, while others helped plan out compositions like this one.
If we look closely, we can see some alterations made to the painting. X-radiography has revealed pentimenti - changes made during the painting process - including the face of a deacon and the positions of children in the foreground. This level of detail shows just how meticulous Rubens was in his work.
Saint Bavo is received by Saints Amand and Floribert hangs in The National Gallery on Trafalgar Square, London — free to enter. Point your phone at any artwork there and audioguide.london plays a free audio guide in six languages — no app download needed.