While reading Tiziano Dorandi’s fascinating work, Le stylet et la tablette, on how ancient authors composed their works, I find on p.113 a little snippet.
Cicero sent his works to Atticus for correction and publication. It seems that Atticus would ‘mark’ the work in red ink, just like a modern school-teacher.
We learn from Cicero’s letter to Atticus (book 16, 11, 1) that the former pretended to have just the same feelings, as a modern pupil would:
Nostrum opus tibi probari laetur … cerulas enim tuas miniatulas illas extimescebam!
I am glad that my work pleases you … for I was afraid of your little red crayon!
How little some things change down the centuries. Red and black have been the standard colours for inks for centuries, probably because they were easiest to prepare. I wonder whether Roman schoolboys did homework? There are certainly schoolboy exercises among the papyri from Egypt.