The German title of 'Carnival' is 'Fastnacht' which refers to the climax of the Carnival season of fancy dress parties, masked balls and street processions with wild music and dancing, which take place in Catholic countries between mid-January and the beginning of Lent on Ash Wednesday. Fastnacht thus traditionally symbolises the vanity and futility and transience of the world. The fact that this carnival scene is taking place indoors maybe related to the fact that in 1920 the Frankfurt police banned all public festivities on grounds of extravagance.
The standing figures are portraits of two important people in Beckmann's life. The woman is Fridel Battenburg, wife of his friend the painter Ugi Battenburg, who had taken him in and looked after him for four years after his discharge from the army. The man is I.B. Neumann, an art dealer who was one of the first to realise the significance of Beckmann's new post-war style and the only dealer prepared to exhibit it before 1919. Their relationship was one of close mutual emotional and intellectual support. The image of these two people in the painting reflects Beckmann's affection for them. The figure on the floor has been identified as Beckmann himself disguised as a clown in a monkey mask and wielding a trumpet with his bare feet. Beckmann seems to be using the image of the Clown or Fool to represent the madness of the world and in very general terms this image of carnival may be a metaphor for the world as a madhouse.
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.125