Hodgepodge 254/365 - Ars Poetica

In 19 B.C.E., Horace wrote a 476-line poem advising poets on the art of writing poetry and drama. Per Wikipedia, it covers three basic topics:

(a) A poem demands unity, to be secured by harmony and proportion, as well as a wise choice of subject and good diction. Meter and style must be appropriate to theme and to character. A good model will always be found in Homer (ll. 1–152).
(b) Dramatic poetry calls for special care - as to character drawing, propriety of representation, length of a play, number of actors, use of the chorus and its music, special features for the satyric type, verse-forms, and employment of Greek models (ll. 153–294).
(c) A poet's qualifications include common sense, knowledge of character, adherence to high ideals, combination of the dulce with the utile, intellectual superiority, appreciation of the noble history and lofty mission of poetry, and above all a willingness to listen to and profit by impartial criticism (ll. 295–476).

In 1926, Archibald MacLeish wrote his own version. Here it is:

Ars Poetica

A poem should be palpable and mute
As a globed fruit,

Dumb
As old medallions to the thumb,

Silent as the sleeve-worn stone
Of casement ledges where the moss has grown—

A poem should be wordless
As the flight of birds.

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A poem should be motionless in time
As the moon climbs,

Leaving, as the moon releases
Twig by twig the night-entangled trees,

Leaving, as the moon behind the winter leaves,
Memory by memory the mind—

A poem should be motionless in time
As the moon climbs.

       *

A poem should be equal to:
Not true.

For all the history of grief
An empty doorway and a maple leaf.

For love
The leaning grasses and two lights above the sea—

A poem should not mean
But be.