Quotations about:
    precept

Whene’er you lecture, be concise: the soul
Takes in short maxims, and retains them whole:
But pour in water when the vessel’s filled,
It simply dribbles over and is spilled.

[Quidquid praecipies, esto brevis, ut cito dicta
percipiant animi dociles teneantque fideles:
omne supervacuum pleno de pectore manat.]

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

Epistles [Epistularum, Letters], Book 2, ep. 3 “Art of Poetry [Ars Poetica; To the Pisos],” l. 335ff (2.3.335-337) (19 BC) [tr. Conington (1874)]
    (Source)

On teaching moral lessons when writing.

(Source (Latin)). Other translations:

In all thy preceptes be thou briefe that learners quicklye maie
Conceive thy words, and that the same in faithfull mynde to staye.
What s'euer is superfluose, to muche, and oftens tould,
Doth fill the hearer paste the brim that long he cannot hould.
[tr. Drant (1567)]

Be briefe in what thou wouldst command, that so.
The docill mind may soon thy precepts know,
And hold them faithfully; for nothing rests
But flowes out, that ore swelleth in full brests.
[tr. Jonson (1640)]

Let all your precepts be succinct and clear,
That ready wits may comprehend them soon,
And faithfull memories retain them long;
For superfluities are soon forgot.
[tr. Roscommon (1680)]

Short be the precept, which with ease is gain'd,
By docile minds, and faithfully retain'd.
If in dull length your moral is exprest,
The tedious wisdom overflows the breast.
[tr. Francis (1747)]

Short be your precepts, and th' impression strong,
That minds may catch them quick, and hold them long!
The bosom full, and satisfied the taste,
All that runs over will but run to waste.
[tr. Coleman (1783)]

In precept be concise: what thus is told
The mind shall grasp with ease, with firmness hold:
While all, that's heap'd superfluous, shocks the taste,
From memory's tablet fades, and runs to waste.
[tr. Howes (1845)]

Whatever precepts you give, be concise; that docile minds may soon comprehend what is said, and faithfully retain it. All superfluous instructions flow from the too full memory.
[tr. Smart/Buckley (1853)]

Let all your precepts be concise, for these
Stick to men's minds, and they are grasped with ease;
But tax too much their memory or their taste,
And all your surplus words run off to waste!
[tr. Martin (1881)]

Whenever you instruct, be brief, so that what is quickly said the mind may readily grasp and faithfully hold: every word in excess flows away from the full mind.
[tr. Fairclough (Loeb) (1926)]

Whatever the lesson you would convey, be brief, that your hearers may catch quickly what is said and faithfully retain it. Every superfluous word is spilled from the too-full memory.
[tr. Blakeney; ed. Kramer, Jr. (1936)]

But when you instruct, be brief, so the mind can clearly
Perceive and firmly retain. When the mind is full,
Everything else that you say just trickles away
[tr. Palmer Bovie (1959)]

Be concise in all you teach, so that attentive minds
can quickly see your point and remember it correctly;
everything poured into a full memory will flow back out.
[tr. Fuchs (1977)]

Whichever,
Say it quickly, so he who runs can listen, and hear, and learn,
And be better for learning. A bursting head
Opens like a bladder, and leaks away.
[tr. Raffel (1983 ed.)]

As for instruction, make it succinct, so the mind
Can quickly seize on what's being taught and hold it;
Every superfluous word spills out of a full mind.
[tr. Ferry (2001)]

When you are giving advice, be brief, to allow the learner
quickly to seize the point and then retain it firmly.
If the mind is full, every superfluous word is spilt.
[tr. Rudd (2005)]

When you give instruction, be brief, what’s quickly
Said the spirit grasps easily, faithfully retains:
Everything superfluous flows out of a full mind.
[tr. Kline (2015)]