Consider, further, their variety, and diverse beauty, and multitude, and how through them resurrection is exhibited, for a pattern of the resurrection of all men which is to be. For who that considers it will not marvel that a fig-tree is produced from a fig-seed, or that very huge trees grow from the other very little seeds? And we say that the world resembles the sea. For as the sea, if it had not had the influx and supply of the rivers and fountains to nourish it, would long since have been parched by reason of its saltiness; so also, the world, if it had not had the law of God and the prophets flowing and welling up sweetness, and compassion, and righteousness, and the doctrine of the holy commandments of God, would long ere now have come to ruin, by reason of the wickedness and sin which abound in it. And as in the sea there are islands, some of them habitable, and well-watered, and fruitful, with havens and harbors in which the storm-tossed may find refuge, — so God has given to the world which is driven and tempest-tossed by sins, assemblies — we mean holy churches — in which survive the doctrines of the truth, as in the island-harbors of good anchorage; and into these run those who desire to be saved, being lovers of the truth, and wishing to escape the wrath and judgment of God. And as, again, there are other islands, rocky and without water, and barren, and infested by wild beasts, and uninhabitable, and serving only to injure navigators and the storm-tossed, on which ships are wrecked, and those driven among them perish, — so there are doctrines of error — I mean heresies — which destroy those who approach them. For they are not guided by the word of truth; but as pirates, when they have filled their vessels, drive them on the fore-mentioned places, that they may spoil them: so also, it happens in the case of those who err from the truth, that they are all totally ruined by their error.
~Theophilus- To Autolycus Book II Vol. 2