Without the slightest pause of transition men passed through the most contradictory systems of belief.

Still, a few general characteristics may be observed; in the first place, heresies are no longer metaphysical subtleties as in earlier days; Arius and Priscillian, Nestorius and Eutychus are dead indeed.

In the second place, they no longer arise in the upper and governing class, but proceed especially from the inferior clergy and the common people.

The blows which actually threatened the Church of the Middle Ages were struck by obscure laboring men, by the poor and the oppressed, who in their wretchedness and degradation felt that she had failed in her mission.
No sooner was a voice uplifted, preaching austerity and simplicity, than it drew together not the laity only, but members of the clergy as well.
Toward the close of the twelfth century we find a certain Pons rousing all Perigord, preaching evangelical poverty before the coming of St.
Francis.[14] Two great currents are apparent: on one side the Cathari, on the other, innumerable sects revolting from the Church by very fidelity to Christianity and the desire to return to the primitive Church.
Among the sects of the second category the close of the twelfth century saw in Italy the rise of the _Poor Men_, who without doubt were a part of the movement of Arnold of Brescia; they denied the efficacy of sacraments administered by unworthy hands.[15] A true attempt at reform was made by the Waldenses.

Their history, although better known, still remains obscure on certain sides; their name, _Poor Men of Lyons_, recalls the former movement, with which they were in close agreement, as also with the Humiliants.