Here is an essay by one of the founders of Dada, Tristan Tzara (Sami Rosenstock a.k.a. Samuel Rosenstock; 1896 – 1963), who rambles on about the origins of the movement:
"Dadaism is a characteristic symptom of the disordered modern world...To the exiled intellectuals of Switzerland, humanity seemed to have gone insane - all order was crashing to destruction, all values were turned upside down - and, in accordance with this spirit, they began a set of wild practical jokes, elaborately silly meetings and fantastic manifestos which burlesqued, in their violence of the life around them."