There is, however, an historical work of the Society which has no peer in literature: the great hagiological collection known as the "Acta Sanctorum" of the Bollandists, which was begun in the first years of the seventeenth century, and is still being elaborated. It consists at present of sixty-four folio volumes. This vast enterprise was conceived by the Belgian Father Rosweyde, but is known as the work of the Bollandists, from the name of Rosweyde's immediate successor, Bollandus. When the first volume, which was very diminutive when compared with the present massive tomes, was sent to Cardinal Bellarmine, he exclaimed: "this man wants to live three hundred years." He regarded the plan as chimerical, but it has been realized by a self-perpetuating association of Jesuits living at Brussels. When one member is worn out or dies, someone else is appointed to fill the gap, and so the work goes on uninterruptedly. The two first volumes, containing pages, which appeared in 1643, aroused the enthusiasm of the scientific world, and Pope Alexander VII publicly testified that "there had never been undertaken a work more glorious or more useful to the Church." In other fields of work the Society has not been idle. Even the acrid "Realencyclopädie fur protestantische Theologie und Kirche" says (VIII, 758), "the Order has not lacked scholars. It can point to a long series of brilliant names among its members, but they have only given real aid to the advancement of science in those spheres which have close connection with the doctrines of the Church, such as mathematics, the natural sciences, chronology, explanation of classical writers and inscriptions. The service of Jesuit astronomers like Christopher Schlüssel (Clavius), the corrector of the calendar; Christopher Schreiner, the discoverer of the sun spots; Francesco Da Vico, the discoverer of a comet and observer of the transit of Venus; Angelo Secchi, the investigator of the sun, and a meteorologist, are universally acknowledged. And no less credit is given to the services of the Order afforded by the optician Grimaldi; and that much praised all-round scholar and universal genius (Doctor centum artium) Athanasius Kircher. Among the classical writers is Angelo Mai."