In 1825 Father Moreau was appointed as seminary professor of philosophy of Tessé which was an annex the the Major Seminary of St. Vincent. M. Mollevaut, his spiritual director wrote to him that the purpose of the seminary was not only intellectual development but to develop priests who were men of prayer. In line with this Fr. Moreau stressed the observance of the Month of Mary which had been approved by Pius VII in 1815. In his teaching Fr. Moreau found himself upholding the primacy of the Pope against Gallicanism. He was however, admonished by his spiritual director to use prudence and not take sides in the controversy.

1825 Fr. Moreau was appointed as professor of dogma, St. Vincent’s Seminary, Le Mans. Most of the priest professors and M. Bouvier, the superior had at one time been his teachers. Fr. Moreau recognized the importance of science and convinced the Bishop to begin the teaching of physics in the seminary. Now he took a definitive stand against Gallicanism. In one of his notes we read, "The Monarchy of the Church: In founding the Church is was the Lord's will to establish a monarchy". Partly due to this stand, he was removed from teaching dogma and assigned to teach Scripture in 1830. In his sermons to the seminarians he constantly made them aware of the high dignity of the priesthood which was to glorify God, save souls and to become holy.

Bishop Philippe Carron (1829-1833) was instrumental in Divine Providence for leading Father Moreau to do apostolic work outside the Seminary. For example, between 1830-31 the government subsidy to the Bishop, parishes and schools were reduced or eliminated. Bishop Carron was determined to save his schools run by the Christian Brothers so he asked Father Moreau to go begging for him. Fr. Moreau at first hesitated but when the bishop insisted Fr. Moreau knelt before the Bishop and asked for his blessing. Father Moreau was able to raise the amount needed in a few days.

Another example will suffice. On May 9, 1832 he sent a circular letter to all the priests with the approval of the Bishop suggesting what could be done for the priests retirement. He proposed the establishment of a Retirement Home for priests which would be paid for from annual fees paid by the priests who wish to join and donations from benefactors. This proposal was rejected in favor of a retirement fund which would insure the freedom of priests to retire as they choose. In 1833 due to divine providence, Fr. Moreau found himself increasingly involved in projects outside the seminary.

6. Sisters of the Good Shepherd at Le Mans