“When you wish to instruct, be brief; that men’s minds may take in quickly what you say, learn its lesson, and retain it faithfully. Every word that is unnecessary only pours over the side of a brimming mind.”
Quidquid praecipies, esto brevis, ut cito dicta
percipiant animi dociles teneantque fideles:
omne supervacuum pleno de pectore manat.
Source: Ars Poetica, or The Epistle to the Pisones (c. 18 BC), Lines 335–337; Edward Charles Wickham translation