2. But the notion of Purgatory was necessarily incomplete when it gained importance, for humanity at that time had no other idea of Hell than that of fire and they therefore naturally conceived of Purgatory as a lesser and shorter Hell; they supposed that souls were burned there, but with a burning less intense. And as the idea of progress is irreconcilable with the dogma of eternal punishment, they held that souls are delivered from Purgatory not as a consequence of their own moral improvement, but as an effect of the prayers that are said or paid for, by their friends on Earth for their deliverance.
The primary idea of Purgatory was true and good; but the same cannot be said of the consequences deduced from it, and the abuses of which it has thus become the source. Through the custom of paying for prayers on behalf of the souls in Purgatory, this doctrine has become a mine even more productive to those who work it than that of Hell. *
* The doctrine of Purgatory has also given rise to the scandalous sale of indulgences, which pretend to enable people to purchase, with money, their entrance into Heaven. This gross abuse was the determining cause of the Reformation, and led to the rejection of the idea of Purgatory by Luther.