He preferred to preach to the poor; his sermons, taken largely from the Prophets and Sapiential Books, breathe the tenderest human sympathy.

At the time Peter entered the Order, the reform of the "Discalced Friars" consisted of the Custody of the friaries in Spain and Santa Maria Pietatis in Portugal, all subject to the Minister General of the Observants.

[3] In 1538 Peter was made minister provincial of the Franciscan province of St Gabriel of Estremadura but resigned when his plans to enforce severe rules among the friars were opposed,[2] and he retired with John of Avila into the mountains of Arrábida in Portugal, where he joined Friar Martim de Santa Maria in a life of eremitical solitude.

[4] Friaries were established at Pedrosa, Plasencia and elsewhere; in 1556 they were made a commissariat, with Peter as Commissary, and in 1561 a religious Province under the title of St Joseph.

In 1562 the Province of St Joseph was put under the jurisdiction of the Minister General of the Observants, and two new custodies were formed: St. John Baptist in Valencia and St. Simon in Galicia (see Friars Minor).

He wrote a Treatise on Prayer and Meditation, which was considered a masterpiece by Teresa, Francis de Sales and Louis of Granada.

[10] Some Traditionalist Catholics continue to observe versions of the General Roman Calendar of the 1670-1969 period, of which the 1960 version is incorporated into the 1962 Roman Missal that Pope Benedict XVI permitted to be used by all Latin Church priests for Masses without the people and, under the conditions indicated in article 5 of his motu proprio Summorum Pontificum, in Masses with the people.