Irony is an existential determination, and nothing is more ridiculous than to suppose that it consists in the use of certain phraseology, or when an author congratulates himself upon succeeding in expressing himself ironically. Whoever has essential irony has it all day long, not bound to any specific form, because it is the infinite within him. Irony is a specific culture of the spirit.
–Søren Kierkegaard, Concluding Unscientific Postscript (trans. David Swenson)