Having sketched the character of legal enquiry in France before Ivo set to work, it is now necessary to examine Ivo's own education and the sources from which the collections commonly attributed to him were drawn. The chief object is to demonstrate the range of reading upon which he might depend when approaching particular issues, but two other points are of almost equal importance. First, the enquiry will underline the sharp differences which mark his enterprise from what had gone before. Second, the interrelation of the sources used is an essential preliminary to clarifying the much vexed question of Ivo's own part in a number of canonical enterprises which have all been associated with him at various times.
In fact, even Ivo's extant works, while almost without exception written at Chartres, can be linked directly to his time at St Quentin. Already an abbot, Ivo was also a teacher of ‘sacra scriptura’; among his pupils were John of Warneton, whose Life was quoted above, and Lambert, the future bishop of Arras. Nearby Beauvais was a centre of theological and perhaps also legal scholarship, where Ivo presumably met both Roselyn and Ernulf of Rochester, two scholars with whom he kept contact later. In this environment, Ivo wrote his earliest extant work, an elaborate lettertract on the Eucharist. It is the only work by Ivo which can positively be dated to his years at St Quentin, but still constitutes clear evidence how Ivo engaged in this great public debate.