Use both ends of the pencil if you hope
to write what gets read twice.

[Saepe stilum vertas, iterum quae digna legi sint
scripturus.]

Horace (65-8 BC) Roman poet, satirist, soldier, politician [Quintus Horatius Flaccus]

Satires [Saturae, Sermones], Book 1, # 10, “Nempe incomposito,” l. 72ff (1.10.72-73) (35 BC) [tr. Matthews (2002)]
    (Source)

The Romans used a stylus to write on waxed tablets; analogous to a modern pencil with eraser, one end of the stylus was pointy to engrave the letters, the other flat to smooth the wax out for revision.

(Source (Latin)). Alternate translations:

For nowe, who lookes to beare the bel, his doyngs he muste cull,
At home with hym, and better adde, then he dyd erste out pull.
[tr. Drant (1567)]

He that would write what should twice reading stand,
Must often be upon the mending hand.
[tr. A. B.; ed. Brome (1666)]

When you design a lasting Piece, be wise,
Amend, Correct, again, again Revise.
[tr. Creech (1684)]

Would you a reader's just esteem engage?
Correct with frequent care the blotted page.
[tr. Francis (1747)]

Spare not erasion, ye that wish your strain,
When once perused, to be perused again.
[tr. Howes (1845)]

You that intend to write what is worthy to be read more than once, blot frequently.
[tr. Smart/Buckley (1853)]

Ofttimes erase, if you intend to write what may prove worth a second reading.
[tr. Millington (1870)]

Oh yes! believe me, you must draw your pen
Not once nor twice but o'er and o'er again
Through what you've written, if you would entice
The man that reads you once to read you twice.
[tr. Conington (1874)]

Often must you turn your pencil to erase, if you hope to write something worth a second reading.
[tr. Fairclough (Loeb) (1926)]

You’ll often have to erase if you mean to write something
Worth reading twice.
[tr. Palmer Bovie (1959)]

Keep reversing your pencil if you'd like to write a piece
worth reading twice.
[tr. Fuchs (1977)]

For you must often
reverse your stylus and revise, if you wish
to write things worthy of being reread.
[tr. Alexander (1999)]

If you hope to deserve a second reading you must often employ
the rubber at the end of your pencil.
[tr. Rudd (2005 ed.)]

If you want to write what’s worth a second reading,
You must often reverse your stylus, and smooth the wax.
[tr. Kline (2015)]