Symbol Analysis
We know that Petrarch's Laura is meant to be Laura de Noves, the very real wife of the Marquis de Sade (the ancestor of the infamous one), but she's also much more than that. In the Canzoniere, Laura is the epitome of all that is womanly, pure and beautiful. It's no wonder that so many people over the centuries have doubted her existence. Who could possibly live up to that ideal?
But Laura also embodies something much darker and more difficult for Petrarch. For him, she is discontent, frustrated sexual desire, constant yearning. In short, she is madness. While his love for her leads Petrarch to establish new forms of poetry and to create the most beautiful and ground-breaking verse the world had ever seen, it also led him to distrust his judgment and doubt his own talent (see Canzone125)—or even his ability to keep on living.
This doesn't stop Petrarch from crushing on her, though, especially because of her beauty. You may notice in this particular poem that we never really get a good glimpse of Laura, but we do see a whole lot of nature where her body should be. Sometimes it's even a little difficult to see where Laura ends and the natural world begins:
[…] kind branch on which it pleased her
(I sigh to think of it)
to make a column for her lovely side;
and grass and flowers which her gown,
richly flowing, covered
with its angelic folds (4-9)
So who's doing the beautifying here: the woman or the flowers and trees? It's quite hard to tell, and it doesn't get easier. By the time we get to stanza 4—where we see the shower o' flowers—Laura is basically nothing more than a bosom, a lap, and some curly blond hair. Petrarch leaves it to the natural world to work its magic on our imaginations.
In the end, Laura really becomes the natural world. If that sounds too bizarre for you, take a look at lines 64-65: "and since then I have loved/ this bank of grass and can find peace nowhere else." Since Petrarch can't have her body, he associates her with the places in nature where she once walked.