From this necessarily brief review of the development of the argument for the existence of a Divinity in Greek and Roman thought, it will be seen that, at one time or another, in a more or less fully developed form, each one of the principal types of the theistic argument received the chief emphasis and had its method enunciated. The pre-Socratic natural philosophers, on the basis of the maxim as old as philosophy itself--Ἀδύνατον γίνεσθαι τι ἐκ μηδενὸς προυπάρχοντος--pointed to an Ἀρχή--a real behind phenomena, a permanent behind the change--and thus pointed to the so-called Aetiological argument founded on the principle of causality. Socrates, with his pre-eminently practical disposition and ethical point of view, saw above all things intention in nature, and so from the consideration of this choice and adaptation of means to their end, and the resultant Final Cause he constructs a very complete Teleological argument for the existence of some intelligence behind the visible world. Plato's Ideas, as we have seen, determine the method by which he arrives at his abstract divinity, namely, by the "Idealogical" form of argument based upon a process of generalization. Aristotle, struck by the phenomena of motion in the universe, lays most stress on the course of reasoning which would lead back to the Prime Mover. The Epicureans, subordinating their theology to their ethical theory, and unwilling to allow their deity to interfere with the world or with men's affairs, developed and placed their dependence on the argument from common consent. The Stoics, laying great stress upon the order, proportion and harmony in the world, argued to mind as the reason for this condition of things. But none of these philosophers, in the opinion of the writer, attained to a conception of God which could in any real or accepted sense of the word be called theistic, or which would satisfy a mind accustomed to the idea of the Christian doctrine of God.