of the ecclesiastical
law. "Return to the canon law!" was now the battle-cry. In the Cluniac
circle was coined the principle: _Canonica auctoritas Dei lex est_,
canon law being taken in the Pseudo-Isidorian sense. The programme of
reform thus included not only the extirpation of simony and Nicolaitism,
but also the freeing of the Church from the influence of the State, the
recovery of her absolute control over all her possessions, the liberty
of the Church and of the hierarchy.

As a result, the party of reform placed itself in opposition to those
ecclesiastical conditions which had arisen since the conversion of the
Teutonic peoples. It was, then, a fact pregnant with the most momentous
consequences that Leo IX. attached himself to the party of reform. For,
thanks to him and to the men he gathered round him (Hildebrand, Humbert
and others), their principles were established in Rome, and the pope
himself became the leader of ecclesiastical reform. But the carrying out
of reforms led at once to dissensions with the civil power, the
starting-point being the attack upon simony.

Originally, in accordance with Acts viii. 18 et seq., simony was held to
be the purchase of ordination. In the 9th century the interpretation was
extended to include all acquisition of ecclesiastical offices or
benefices for money or money's worth. Since the landed proprietors
disposed of churches and convents, and the kings of bishoprics and
abbeys, it became possible for them too to commit the sin of simony;
hence a final expansion, in the 11th century, of the meaning of the
term. The Pseudo-Isidorian idea being that all lay control over things
ecclesiastical is wrong, all transferences by laymen of ecclesiastical
offices or benefices, even though no money changed hands in the process,
were now classed as simony (Humbert, _Adversus Simoniacos_, 1057-1058).
Thus the lord who handed over a living was a simonist, and so too was
the king who invested a bishop. On this question the battle began. The
Church at first refrained from contesting the rights of the landowners
over their own churches, and concentrated her attack upon investiture.
In 1059 the new system of papal election introduced by Nicholas II.
ensured the occupation of the Holy See by a pope favourable to the party
of reform; and in 1078 Gregory VII. issued his prohibition of lay
investiture. In the years of conflict that followed Gregory looked far
beyond this point; he set his aim ever