The winter of our discontent
Now is the winter of our discontent
Made glorious summer by this son of York;
And all the clouds that low'r'd upon our house
In the deep bosom of the ocean buried.
Richard, the future king, opens his play not by protesting his discontent, but by celebrating an upturn in his family's fortunes. His brother Edward IV—they're sons of the Duke of York—has wrested the English crown from Henry VI and the Lancastrian house. So those who simply quote "Now is the winter of our discontent" are doing these lines a disservice, since the "now" actually modifies "made glorious" (i.e. "The winter is now made glorious summer"). To translate more loosely: "The oppression of our family, which made life like a long winter, has been turned to a summery contentedness now that my brother is king." Edward's emblem is the sun, and the radiance of his glory has dispelled the clouds that "lowered" (frowned) on the House of York. Richard's string of metaphors runs adrift, though, when he begins talking about burying clouds in the ocean.
But lest we get the idea that Richard couldn't be happier with the current state of affairs, he quickly begins grousing about Edward's decadent ways now that he's king. And from there he moves on to brooding over his own deformity—Richard was born hunchbacked and disfigured. In many respects, it's still winter for the restless Richard, who himself has ambitions for the throne. He attempts to bring on his own summer through manipulation, treachery, and murder, and, for a short time, he succeeds.