Coptic is the final chapter of four thousand years of Egyptian writing. By the early centuries CE the old scripts, hieroglyphic, hieratic and demotic, were the property of a shrinking priestly class, while Greek was the language of administration and increasingly of daily life. Egyptian speakers began writing their own language in Greek letters, adding signs from demotic for the sounds Greek lacked; the system settled at the Greek alphabet plus six or seven Egyptian letters, varying by dialect.
The decisive push came from Christianity: translating scripture demanded a script ordinary believers could learn, and from the third and fourth centuries the Bible was rendered into the Sahidic and later the Bohairic dialect. Monasticism, born in Egypt with Antony and organised by Pachomius, wrote its rules, letters and lives of the fathers in Coptic, and Shenoute of Atripe made it a vehicle of powerful native prose. Because Coptic writes vowels, unlike its Egyptian ancestors, it preserved at last the vocalisation of the Egyptian language, which made it the indispensable key when Champollion approached the hieroglyphs, and it remains the living voice by which scholarship hears ancient Egyptian sounds.