St Philippa was born in the province of Rieti (Italy) to the noble Mareri family at the end of the twelfth century. During her humanistic education, despite the great wealth in which she lived, at the age of 18 she decided to consecrate herself to God, but her family strongly opposed it. After meeting St. Francis in 1225, she ran away from home with her sister and other companions with whom she began her monastic life in a natural cave on Monte Sella – today called "Grotta di Santa Filippa-The cave of St Philipa".
Her brothers, Tommaso and Gentile, were unable to change her mind, so in 1228, after the death of her parents, in front of the representative of the local Church and the Friars Minor (Blessed Ruggero da Todi), they entrusted her with the monastery of Villa Casardita, with the ancient church of San Pietro de Molito (today Borgo S. Pietro).
St Philippa moved there with her companions, organising a cloistered life according to the Rule that St. Francis had entrusted to St. Clare and the Sisters of San Damiano. The spiritual care of the monastery was entrusted to Blessed Roger of Todi: the place became a school of holiness, and St Philippa was a true teacher of spiritual life.
The main occupation of the community was the worship and praise of God, liturgical life, reading and studying the Bible. Alongside spiritual activity, work was held in high esteem, together with service to the poor and the apostolate. In the monastery, medicines were prepared to be distributed free of charge to the sick. With her words, but above all with the fervour of her charity and the lifestyle modelled on St. Francis and St. Clare, he brought to life some pages of the Gospel in a world that had forgotten them.
St Philippa died young of consumption (Tubercolosis), on the 16th February, 1236, but her reputation for holiness spread immediately. Her tomb soon became a destination for pilgrimages and heavenly graces and favours bestowed by God through the intercession of His servant began to be recorded.
The title of Saint appears for the first time in a Bull of Innocent IV issued in 1247, when just ten years had passed since her passing: for this reason, St. Philippa Mareri is considered by some to be the first saint of the Second Franciscan Order.
Devotion to her grew from year to year, not only in her area (Province of Rieti and surroundings), but also in other countries and continents, thanks to the veneration of migrants who kept St. Philippa in their hearts and prayers and found comfort and support in her in difficulties.
In 1706, his mortal remains were reconnaissed, and his incorrupt heart was found.
She was inscribed in the Roman Martyrology as Blessed in 2004. On the 8th May, 2007, Cardinal José Saraiva Martins, Prefect of the Congregation for the Causes of Saints, notified the Bishop of Rieti and the apostolic administrator of Sulmona-Vasto that Filippa was to be considered and venerated as a saint "ad effectum de quo agitur."
A curiosity. Thanks to St Philippa, the Borgo San Pietro was formed around her monastery of San Pietro de Molito, on the banks of the river Salto. This river was dammed in 1940 with a 90-meter-high dam to create Lake Salto, the largest artificial basin in Lazio. The ancient centre of Borgo San Pietro and the monastery of Filippa were thus submerged by the waters, to be rebuilt near the right bank of the lake, at a higher altitude (580 m). The ancient chapel that housed the relics of the saint was restored in the new church with the original stones and decorated, after their detachment, with the same frescoes dating back to 1400 and 1500.
Only in dry summer periods, when the level of the lake drops significantly, do the remains of submerged buildings resurface.