"there are strange things and unaccountable agencies in nature: He only who dwells between the Cherubim can unriddle them"
Though cherubs these days have become confused with putti - chubby angels arrested in perpetual toddlerhood - their biblical forebears were rather fearsome creatures. The prophet Ezekiel describes them as possessing four heads (of a lion, an ox, an eagle and a man), the feet of a calf and four wings covered in multitudinous eyes. They frequently appear as guardians and stand watch over the throne of God, to whom Robert is referring here.