The History of the Paragraph

J.E. Sandys, The History of Classical Scholarship, 1.1.7:

“The writings of Heracleitus are described (Rhet. Iii 5) as hard to punctuate (διαστίξαι), but the only mark of punctuation actually mentioned by Aristotle is the παραγραφή (ib. 8), a short horizontal dash drawn below the first word of the line in which the sentence is about to end. It is from this ancient symbol, which marks the close of the sentence, that we give to the sentence itself, or to a connected group of sentences, the name of a ‘paragraph.’”