Adam first came across John Wyclif whilst the two men were studying at Oxford. They shared a common interest in attacking the successful and increasingly wealthy Friars. Adam owned copies of the writings of both William of StAmour and Richard FitzRalph attacking the Friars and Wyclif had certainly read both works himself. Adam may even have loaned Wyclif his own copies while they were at Oxford. Yet increasngly in the years that followed, the broad thrust of Wyclif's life was to attack not just the Friars, but every aspect of the Church, both spiritual and temporal. He raged against the hierarchy, wealth and the power over secular life that the Church had established and as we have seen (see the section on the 14th Century Church) he was far from alone.

Yet the Church had other things to worry about and just as Wyclif produced his most vociferous attack in 1376, the Pope packed up the papal Court in Avignon to return to Rome and try and re-establish his secular authority (and the taxes that went with that) over the states of central Italy that had risen in open rebellion against him. The fact that once again fiscal matters seemed to be governing the fate of the Church rather than matters spiritual gave extra poignancy to Wyclif's attacks.

Adam now found himself in strident opposition to his former fellow student. He may not have approved of everything the pope was doing, he may have had doubts about the motives behind the return to Rome, but he was now entrenched in the same church hierarchy that Wyclif attacked. He planned his defence of the Church in two stages. The first was vicious but effective, simply to identify the key elements of Wyclif's philosophy that could be identified as heretical, and get him condemned by the Church both in England and Rome.

The second and perhaps the more interesting part of the enterprise was to try and set out in writing, through argument and debate of the issues, a definitive defence of the power of the Church under God on earth. This became the vast Defence of Ecclesiastical Power and it was a volume that would have a profound impact in denying the truth of Wyclif's argument.