These two hymns, inscribed on separate stone blocks of the Athenian Treasury, are the oldest surviving examples of ancient Greek musical annotations. Their importance is great, not only for the history of ancient Greek music, but also for our knowledge of Apollo's cult. They mention myths and events related to Apollo, and summon the god to help and protect. One of the inscriptions bears letters of the Ionic alphabet, which transcribed the musical notes for the song. The other inscription has dots and letters representing the notes for the musical instruments. These symbols have been translated into modern musical notes, but the rhythm of the piece remains unknown. The first hymn was written by an Athenian composer and performed during the Pytha?s, the formal procession of the Athenians at Delphi, in 138 BC. The second hymn was performed in the same procession ten years later.