Thomas was born sometime between 1185 and 1190, into the noble family of the Conti dei Marsi at Celano in the Province of the Abruzzi.

He received a sound liberal arts education, possibly at the Benedictine monastery of Saint John the Baptist near Celano.

His familiarity with monastic tradition suggests that he may have studied at Monte Cassino, Rome or Bologna.

Many researchers of the early history of the Franciscan order believe that Brother Leo, and Rufinus of Assisi, associates of Francis, were the source of the material for the Vita Secunda.

[5] Thomas also wrote Fregit victor virtualis and Sanctitatis nova signa in honor of Francis.