Bentley's "Dissertation upon the Epistles of Phalaris", published in 1699, proved that the letters in question, supposedly written in the 6th century BCE by the Sicilian tyrant Phalaris, were actually a forgery produced by a Greek sophist in the 2nd century CE. Bentley's investigation of the subject is still regarded as a landmark of textual criticism. He also showed that the sound represented in transcriptions of some Greek dialects by the letter digamma appeared also in Homeric poetry, even though it was not represented there in writing by any letter.