Does the Plowman's section of the "General Prologue" in "The Canterbury Tales" teach us a lesson about life?
A trewe swynkere and a good was he,
Lyvynge in pees and parfit charitee.
The plowman is a natural, good worker: he toils hard for his living (plowing the fields) and he lives in peace and perfect charity, just like the Parson, who is described before him. And, like the Parson,
God loved he best with al his hoole herte
At alle tymes, thogh him gamed or smerte,
And thanne his neighebor right as hym-selve.
He loves God with his whole heart even if it hurt ("smerte") him, and loved his neighbour as himself.
The lesson of this little mention of the Plowman, I think, comes from a comparison with his brother the Parson. We expect the Parson to be peaceful, charitable and pious - of course: he's a man of God! But the lesson of the Plowman, who, remember, never actually tells a tale or features within the tales, is that you don't have to be a man of God to be a godly man.
The Plowman, in other words, is an example of how you can be virtuous even when only of low social status - and of simple means.