"No," Picasso replied, "you did", his wit fizzing with the anger that animates the piece.
Work started weeks after German bombers had unleashed an early dose of Blitzkreig on the Basque town from which the work takes its name.
As in Picasso's cubist days, there are symbols and broken shapes aplenty, but with Guernica there is no need to decipher.
Flailing bulls and horses show that the visceral horrors of war are not just an affront to human civilisation, but to life.
With the help of Stepney trade unionists, keen to raise awareness of Spain's civil war, in 1939 Guernica came to Whitechapel art gallery.
Next week the gallery reopens after an overhaul, and a full-size tapestry copy will form part of an installation by artist Goshka Macuga.
It is borrowed from the UN, where it normally hangs outside the security council chamber. »