On a March day in the year 399 BC, a 70-year-old man stands trial in Athens, a man well known in the city. Even his appearance makes him a curiosity: he looks like a woodland sprite and wanders about in the same threadbare cloak in summer and winter alike. He mostly spends his time in the agora at the centre of the city, surrounded by a large crowd of young people, almost all of whom come from the most respected Attic families. The adolescents join in with enthusiasm and curiosity whenever the old man pursues his favourite pastime and questions locals and foreigners alike, especially the politicians and scholars among them, to find out whether they possess real knowledge. The outcome of this examination usually turns out painfully for the one being questioned.
Although he thus exposes every one of his conversation partners for their ignorance, the questioner astonishingly claims about himself that he knows that he knows nothing.