Even though we disregard philosophical atheism, the definition is somewhat narrow; for in antiquity mere denial of the existence of the gods of popular belief was not the only attitude which was designated as atheism. But it has the advantage of starting from the conception of the ancient gods that may be said to have finally prevailed. In the sense in which the word is used here we are nowadays all of us atheists. We do not believe that the gods whom the Greeks and the Romans worshipped and believed in exist or have ever existed; we hold them to be productions of the human imagination to which nothing real corresponds. This view has nowadays become so ingrained in us and appears so self-evident, that we find it difficult to imagine that it has not been prevalent through long ages; nay, it is perhaps a widely diffused assumption that even in antiquity educated and unbiased persons held the same view of the religion of their people as we do. In reality both assumptions are erroneous: our “atheism” in regard to ancient paganism is of recent date, and in antiquity itself downright denial of the existence of the gods was a comparatively rare phenomenon. The demonstration of this fact, rather than a consideration of the various intermediate positions taken up by the thinkers of antiquity in their desire to avoid a complete rupture with the traditional ideas of the gods, has been one of the chief purposes of this inquiry. Though the definition of atheism set down here might seem to be clear and unequivocal, and though I have tried to adhere strictly to it, cases have unavoidably occurred that were difficult to classify. The most embarrassing are those which involve a reinterpretation of the conception of the gods, _i.e._ which, while acknowledging that there is some reality corresponding to the conception, yet define this reality as essentially different from it. Moreover, the acknowledgment of a certain group of gods (the celestial bodies, for instance) combined with the rejection of others, may create difficulties in defining the notion of atheism; in practice, however, this doctrine generally coincides with the former, by which the gods are explained away. On the whole it would hardly be just, in a field of inquiry like the present, to expect or require absolutely clearly defined boundary-lines; transition forms will always occur.