It is a real difficulty that our sources of information of all the heretics of these centuries are chiefly the writings of their successful opponents--the defenders of the orthodox faith. But much information remains to us from the admissions of her supporters as to the depraved condition of the Church at this period; so that we need not believe the allegations or their opponents that a chief inducement to join heretical sects lay in the greater scope for the indulgence of sin. Charges of immorality against opponents were the stock-in-trade of the controversialist, while the greatest authorities in the Church allow that heresy lived upon the scandals and negligences of the Church. Moreover, based as they were upon opposition to the existing organisation, the doctrines of the various sects had much in common. The Church did not distinguish between them, but excommunicated them all alike. If, however, we would understand the developments of opinion in the succeeding centuries, it is important to discriminate; and a clear distinction can be made between those opponents of the Church whose views were aimed against the development of an extreme sacerdotalism within the Church, and those who, going beyond this negative position, reproduced the Manichæan theories of an early age and threatened to raise a rival organisation to that of the Christian Church. [Sidenote: Anti-sacerdotalists.] The object which those who belonged to the first of these divisions set before themselves, was to get behind the elaborate organisation which the Church had built up and which, instead of being a help to lead man to God, had now become a hindrance by which the knowledge of God was actually obscured. They would therefore sweep away all this machinery and return to the Christianity of apostolic times. Their objection was primarily moral, but it soon became doctrinal; and among the heretics of this class there was revived the Donatist theory that the sacraments depend for their efficacy on the moral condition of those who administer them. The campaign of the Church reformers against clerical marriage seemed directly to support this view; but the canons which forbade any one to be present at a Mass performed by a married priest had to be explained away as a mere enforcement of discipline; and in 1230 Gregory IX definitely laid it down that the suspension of a priest living in mortal sin merely affects him as an individual and does not invalidate his office as regards others. But such declarations did nothing to meet the common feeling of the great incompatibility between the awful powers with which the Church clothed her ministers and the sinful lives led by a large proportion of the existing clerical body. [Sidenote: Extreme examples.]