- I met a traveller from an antique land
Who said: Two vast and trunkless legs of stone
Stand in the desert. Near them on the sand,
Half sunk, a shatter'd visage lies, whose frown
And wrinkled lip and sneer of cold command
Tell that its sculptor well those passions read
Which yet survive, stamp'd on these lifeless things,
The hand that mock'd them and the heart that fed.
And on the pedestal these words appear:
"My name is Ozymandias, king of kings:
Look on my works, ye mighty, and despair!"
Nothing beside remains: round the decay
Of that colossal wreck, boundless and bare,
The lone and level sands stretch far away.
--Percy Bysshe Shelley
Here's a good poem to do a comparison with. Shelley and a friend both wrote a poem on the same subject at the same time. They both got published, but nobody remembers the other guy's name or poem except to say that it wasn't as good as Shelley's. Read below asn see if you can see why. What do you like better about either one? Really think about it for three whole seconds before reading what I say.
- In Egypt's sandy silence, all alone,
Stands a gigantic Leg, which far off throws
The only shadow that the Desert knows:
"I am great OZYMANDIAS," saith the stone,
"The King of Kings; this mighty City shows
"The wonders of my hand." The City's gone,
Nought but the Leg remaining to disclose
The site of this forgotten Babylon.
We wonder, and some Hunter may express
Wonder like ours, when thro' the wilderness
Where London stood, holding the Wolf in chace,
He meets some fragments huge, and stops to guess
What powerful but unrecorded race
Once dwelt in that annihilated place.
Both poems are sonnets, and follow the rules of sonnets in rhyme and meter, so we can leave structure out of the equation. I like how the first one tells a story--he met somebody who had seen this, and told him about it. In the second, the poet tells us it exists, but there's less of a personal connection. The first one spends most of the poem describing the statue and inscription. The second one spends almost half the poem moralizing. The first one has several instances of words with double meanings: most notably in the most quoted line of the poem, "Look on my works, ye mighty, and despair!" We can see without anybody telling us that the king meant that we should despair of ever building anything as amazing, but also see the ironic message that as great as we think we are, everything we do will crumble and be forgotten, and so we should despair of making a difference. We don't need him to waste half his space telling us that London will one day be a wasteland.
So to summarize, great poetry is more than just following rules. Word choice matters, but it's really all about seetting a scene and communicating mood. It doesn't have to be explicit, you can hint at things and the reader can figure them out. If you want to say everything and be very clear and precise, you should use prose instead.