Ancient Greek and Latin were written with no spaces at all

Classical scribes ran every letter together with no spacing, punctuation, or capitalization, since texts were mainly aids for performers who had already memorized the words. Word spacing spread only after Irish and Anglo-Saxon monks, copying Latin as a foreign language, began inserting gaps to make unfamiliar text readable. The habit took until the 13th century to become standard across Europe.

— Paul Saenger, Space Between Words: The Origins of Silent Reading — Stanford University Press, 1997
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