Combine thyme, sage, garlic, salt and pepper in a food processor, and pulse to combine. Stream in olive oil and pulse to make a paste.
Rinse the pork, and dry it very well with paper towels. Massage the herb paste all over the meat, making sure to coat both the middle and the crevices between the ribs. Place the roast in a large roasting pan, and allow to marinate and come to room temperature, approximately an hour.
Heat oven to 450.
Roast the pork for 20 minutes, then turn the heat down to 350 and roast approximately 1 1/2 to 2 hours longer, or until the meat, measured between the bones, registers 140 on an instant-read thermometer. Let rest 15 to 20 minutes before carving.