St Placid and his companions, Martyrs
The holiness of St. Benedict in his grotto at Subiaco soon drew around him many disciples, among whom the two greatest were St. Maurus, apostle of the Benedictine Order in France and St. Placid. Both were committed to the care of the holy Patriarch, the former at twelve years of age and the latter when a child of four years old, by their parents who belonged to the most illustrious patrician families of Rome; under the guidance of such a master, they made rapid progress in holiness.
St. Benedict had a special predilection for young Placid, and just as the Saviour chose certain of His disciples to be witness of His miracles, so he liked to be accompanied by the pious child when God gave him miracles to work. On one occasion while drawing water from the lake of Subiaco, Placid fell in, and the waves carried him far from the shore. The man of God sent Maurus who, walking miraculously on the waters, saved him.
Placid and Maurus followed St. Benedict to Monte Cassino.
To-day's Office and Mass celebrate the memory of several Christians who were put to death in Sicily about 541 by Saracenic pirates. According to tradition, these martyrs were St. Placid, his sister, and the monks which St. Benedict had sent to Sicily with him.
Salus autem justorum a Domino: et protector eorum est in tempore tribulationis. * Noli aemulari in malignantibus: neque zelaveris facientes iniquitatem.
But the salvation of the just if from the Lord: and He is their protector in the time of trouble. * Be not emulous of evildoers; nor envy them that work iniquity.
(Psalm 36:39,1 from the Introit of Mass)
Deus, qui nos concedis sanctorum Martyrum tuorum Placidi et sociorum ejus natalitia colere: da nobis in aeterna beatitudine de eorum societate gaudere.
O God, who grantest us to celebrate the heavenly birthdays of Thy holy martyrs Placid and his companions, vouchsafe that we may enjoy their fellowship in everlasting bliss.
From the Catholic Encyclopaedia: http://www.newadvent.org/cathen/12142b.htm