As a Surrealist, many of Magritte's paintings depict dreamlike scenarios (albeit in a very realistic and detailed manner). As such, his art work is often considered to be far removed from the realities of political life. By contrast, On the Threshold of Liberty is considered to be one of Magritte's most controversial, and most politicised, art works.

As soon as the viewer sees On the Threshold of Liberty, it is clear why this picture might be a controversial one. This oil on canvas painting depicts a cannon pointed at a set of paintings, panels, or views seen through windows. The cannon is aimed immediately at what is either a blue sky with fluffy clouds seen through a window or a painting of the sky.

Other paintings surrounding the canon include a naked female torso in a classical style and an abstract pattern featuring ripples and spheres. The theme of the canon makes it obvious why a new version of On the Threshold of Liberty was commissioned on the cusp of the Second World War: this painting arguably perfectly captures the tensions and anxieties of the pre-war period.

This compelling and thought provoking painting has inspired many other artists to create their own works. Most notably perhaps, in 1983, the American composer Mark Isham composed some music inspired by the painting (and he also gave the music the same title, On the Threshold of Liberty). This composition remained a popular fixture of radio programmes and more for more than two decades. Sadly, On the Threshold of Liberty is a painting that remains relevant today. It could be compared to Guernica by Pablo Picasso as both are works of art that illustrate - and warn against - the horrors of war.