Put the chickpeas, garlic, sage, and bay leaves in a large pot and add 10 cups cold water. Bring the water to a boil, then adjust the heat so the water barely bubbles, and cover. Start checking the chickpeas after 30 minutes, and every 15 minutes or so after that. When they can be broken but aren’t yet fully tender, add a large pinch of salt and several grinds of black pepper. Depending on the chick-peas, they may take over 4 hours. Continue cooking and checking until the beans are done the way you like them. Taste and adjust the seasoning, then drain, reserving the cooking liquid; discard the bay leaves and sage.
Rinse the pot, add the oil, and turn the heat to medium. When it’s hot, add the onion, carrots, and celery and sprinkle with salt and pepper. Cook, stirring occasionally, until the vegetables are soft, 5 to 10 minutes.
Turn off the heat and add the chickpeas and 8 cups of the cooking water (or all the cooking water plus enough tap water to equal 8 cups). Use a potato masher right in the pot to break up enough of the chickpeas to thicken the liquid, but leave most of them whole.
Return the soup to a boil. Add the pasta and cook, stirring occasionally, for 5 minutes, then start tasting. Cook until the pasta is tender but still has some bite. Taste and adjust the seasoning, then serve hot, garnished with the parsley and a drizzle of olive oil.