First Georgic [excerpt]

When spring begins and the ice-locked streams begin
To flow down from the snowy hills above
And the clods begin to crumble in the breeze,
The time has come for my groaning ox to drag
My heavy plow across the fields, so that 
The plow blade shines as the furrow rubs against it.
Not till the earth has been twice plowed, so twice
Exposed to sun and twice to coolness will
It yield what the farmer prays for; then will the barn
Be full to bursting with the gathered grain,
And yet if the field's unknown and new to us,
Before our plow breaks open the soil at all,
It's necessary to study the ways of the winds
And the changing ways of the skies, and also to know
The history of the planting in that ground,
What crops will prosper there and what will not.
In one place grain grows best, in another, vines;
Another's good for the cultivation of trees;
In still another the grain turns green unbidden.