From Soren Kierkegaard’s The Concept of Irony (1841):
When Socrates declared that he was ignorant, he nevertheless did know something, for he knew about his ignorance; on the other hand, however, this knowledge was not a knowledge of something, that is, did not have any positive content, and to that extent his ignorance was ironic. . . . If his knowledge had been a knowledge of something, his ignorance would merely have been a conversational technique. His irony, however, was complete in itself. Inasmuch, then, as his ignorance was simultaneously earnest and yet again not earnest, it is on this prong Socrates must be held. To know that one is ignorant is the beginning of coming to know, but if one does know more, it is merely a beginning. This knowledge was what kept Socrates ironically afloat.