There was, in the first place, an increased emphasis laid upon this line of thought, in common with religious subjects in general, and the reasons for the belief in the existence of the gods (for the Greek schools never transcended polytheism--when they speak of θεός they mean simply the abstract divinity of the many separate divinities) seems, so far as we may judge from the comparatively scanty remains that have come down to us, to have been discussed at great length; critically and negatively by the Sceptics, positively and apparently with full conviction by the Stoics, and with a curious mixture of both of these attitudes by the Epicureans. These latter, if the reported doctrine of Epicurus himself be trustworthy, denied the popular gods, and, in order to insure freedom, rejected the Stoic doctrine of providence; but, on the other hand, asserted a belief in gods whose essential characteristics are immortality and perfect happiness (to insure which they must care nothing for the world or for men), and whose existence was held to be proven on the basis of the common consent of all men ("_Argumentum e Consensu Gentium_"). This argument is the result of a "natural idea" or "pre-notion," which Epicurus called πρόληψις;--"that is, an antecedent conception of the fact in the mind, without which nothing can be understood, inquired after, or discoursed on."[22] The Stoics, on the other hand, with their strong conviction of providence working in the world, were rather inclined to deny the validity of this argument from common consent, and rested their belief in the gods, as Cicero makes his Stoic do in _De Natura Deorum_,[23] on the evidence of design and purpose in the universe, but by this process succeeded only in proving to their own satisfaction that the world is divine--a fatalistic pantheism which roused the ire of the Epicurean and Sceptic alike, and which even Cicero seemed hardly to be able to accept.