And the cares that infest the day, (line 42)
Another strong word choice from Longfellow. "Infest" is just such a nasty, gnarly word, packed with gross images of rats and roaches and pests of all kind. If someone told you that you had an infestation, you'd want to get to the doctor or the exterminator quick, right? This is a great example of how a single word can drive home a theme like suffering. We get a quick, visceral image of how much it can stink to be alive, to have to slog through the day.