In a 4-quart soup pot or Dutch oven, warm the olive oil over medium heat. Stir in the onion, celery, carrots, and salt. Then lower the heat, cover the pot, and let the vegetables sweat until the carrots are fairly tender -- about 10 minutes.
Stir in the garlic, black pepper, cannellini beans, stock, and Italian seasoning. Bring to a boil over high heat. Then lower the heat, partially cover the pot, and let simmer quietly for 20 minutes.
Remove the pot from the heat. Add the arugula leaves, and stir just until the leaves wilt -- about 30 seconds. Taste carefully for seasonings, adding more salt and/or pepper if desired.
To serve: Give each serving a drizzle of high-quality extra virgin olive oil and a scattering of shredded Parmesan cheese.