“To all, proportioned terms he must dispense,
And make the sound a picture of the sense.”
                                
                                
                                
                                
                                    
                                    Haud satis est illis utcunque claudere versum,
Et res verborum propria vi reddere claras;
Omnia sed numeris vocum concordibus aptant,
Atque sono, quaecunque canunt, imitantur.
                                
                            
                                        
                                        Book III, line 365. Compare:
'Tis not enough no harshness gives offense;
The sound must seem an echo to the sense.
Alexander Pope, An Essay on Criticism, Part II, line 164 
De Arte Poetica (1527) 
Context: Tis not enough his verses to complete,
In measure, numbers, or determined feet;
Or render things, by clear expression bright,
And set each object in a proper light:
To all, proportioned terms he must dispense,
And make the sound a picture of the sense.