De Backer left his country to be educated at the Jesuit schools of France (Beauregard, Saint-Acheul) and Switzerland Fribourg.
After schooling, and rather than going to the university, he undertook to visit libraries of France and Belgium in search of books printed by Plantin.
In 1835, he was received into the Society of Jesus (in Rome) by the Superior General, Father John-Baptist Roothaan, who sent him back to Nivelles, in Belgium, for his novitiate (29 June 1835).
He taught three years in the school of Namur (1837-1840), and in 1840, began his studies for the priesthood in Leuven.
For each Jesuit author a short biographical note was given, along with the list of all his writings in their successive editions.