XXVIII. There are those calling themselves Gnostics who are envious of those in their own house more than strangers. And, as the sea is open to all, but one swims, another sails, and a third catches fish; and as the land is common, but one walks, another ploughs, another hunts,—somebody else searches the mines, and another builds a house: so also, when the Scripture is read, one is helped to faith, another to morality, and a third is freed from superstition by the knowledge of things. The athlete, who knows the Olympic stadium, strips for training, contends, and becomes victor, tripping up his antagonists who contend against his scientific method, and fighting out the contest. For scientific knowledge is necessary both for the training of the soul and for gravity of conduct; making the faithful more active and keen observers of things. For as there is no believing without elementary instruction, so neither is there comprehension without science.