Observe further Cf. Sophron., Ep. ad. Serg., who refers to the Duliani (᾽Δουλιανοί); the opinions of Felix and Elipandas, condemned at the Synod of Frankfort; and Thomas Aquinas, III., Quæst. 20, Art. 1. that we may not speak of Him as servant. For the words servitude and mastership are not marks of nature but indicate relationship, to something, such as that of fatherhood and sonship. For these do not signify essence but relation.