Jean Bolland (1596-1665), a Jesuit from Julémont (Liège), was summoned to Antwerp in 1630 to take over Rosweyde's legacy. Under his direction the project was hugely expanded to include not only the saints who are known by a Life but all those saints whose names are documented in calendars, martyrologies and other sources. The first two volumes of the Acta Sanctorum, covering the saints whose memories are celebrated in the month of January, were published in 1643. The 2400 pages, folio size, treat of no less than 1170 saints. If some of them, about whom almost nothing is known, could be dealt with in a short paragraph, those saints who are known from one or more Lives are the object of a 'dossier' in which the text editions are preceded by a historical and philological study of the saint's biography, his Lives and Miracles, and his cult. This decisive improvement had been suggested by Bolland's fellow Jesuit and first collaborator Godfried Henskens, or Henschenius (1601-1681), from Venray (Limburg).