History of the Greek alphabet retained the sound. A symbol based on the left-hand half ( ├ ) of the letter Η was therefore sometimes used to indicate the presence of where necessary, and its absence was indicated by a symbol based on the right half. During the classical period, ΕΙ came to be pronounced and ΟΥ came to be pronounced , Υ having meanwhile moved to . By about 200 BC, a system of diacritical marks was invented, representing the tone accents in use in Ancient Greek. This also helped to indicate the length of the vowels Α, Ι, and Υ in certain cases
History of the alphabet alphabet, in which vowels were accorded equal status with consonants. According to Greek legends transmitted by Herodotus, the alphabet was brought from Phoenicia to Greece by Cadmos. The letters of the Greek alphabet are the same as those of the Phoenician alphabet, and both alphabets are arranged in the same order. However, whereas separate letters for vowels would have actually hindered the legibility of Egyptian, Phoenician, or Hebrew, their absence was problematic for Greek, where vowels played a much more important role. The Greeks used for vowels some of the Phoenician letters representing consonants which weren't used in Greek speech.