178 INTRODUCTION 



at Groningen. And furthermore, while Blaes mentioned the duct in 

 his Medicina Generalis, which appeared in 1661, a year after the dis- 

 covery, he could account for neither the beginning nor the end of 

 the duct.^ 



Meanwhile Steno had gone to Leyden, where he remained from 

 1 660- 1 664. Here he worked under van Home, the surgeon, and 

 Franciscus de la Boe Sylvius, the distinguished anatomist who dis- 

 covered the Sylvian aqueduct. Among his intimate friends were 

 men of widely differing attainments. The brilliant young Dane 

 seems, in fact, to have had a genius for friendship. No fellowship 

 could fail to stimulate reflection which included such men as Jan 

 Swammerdam, the naturalist, whom Steno had previously known at 

 Amsterdam ; Borrichius, his old teacher, who had come from 

 Copenhagen ; Matthias Jacobaeus, Professor at Copenhagen, and 

 later Bishop of Aarhus in Jutland; Peter Schumacher, who later 

 became Count Griffenfeldt and High Chancellor of Denmark ; 

 Jacob Golias, Professor of Arabic at Leyden, and Baruch Spinoza, 

 the philosopher, who was then living at Rijnsburg, a suburb of 

 Leyden. But great as the influence of these men was, it was, 

 perhaps, less telling for his subsequent spiritual development than 

 the religious tolerance which Holland alone of European coun- 

 tries then afforded.^ 



While pursuing his anatomical studies in Leyden, Steno learned 

 of the death of his step-father,=* and thereupon returned to his native 

 city. Disappointed in his expectation of gaining a professorship, 

 Steno set out in the same year, 1664, for Paris, where he and 

 Swammerdam lived with the naturalist Thevenot. It was in the 

 latter's house that Steno delivered his discourse on the anatomy of 

 the brain.* This treatise shares with the Prodromus the virtues of 



1 Maar, op. cit., Vol. I, p. 223; Plenkers, Niels Stensen, pp. 12-14, and Wichfeld, Erin- 

 driiiger om Niels Stensen, pp. 7, 8. 



^ Maar, Opera Philosophica, Vol. I, pp. iv-v. 



' Steno's father died in 1644, and his mother, Anna Nilsdatter, had contracted a second 

 marriage with Johannes Stichman. Her death followed closely upon that of the latter. See 

 Plenkers, Niels Stensen, pp. 3, 22, 25. 



^ Discours sur ranatoinie du cerveau, first printed in Paris in 1669; it is reprinted by 

 Maar, op. cit., Vol. II, pp. 3-35. 



Jacques B^nigne Winslow, a grand-nephew of Steno, and himself a scientist of note, was 

 so impressed by the treatise that he printed it in full in his Exposition Anatomiqtie (Paris, 

 1732), PP' 641-659. The preface of the work closes with this remarkable acknowledgment: 



" Je finis en avertissant avec une sincere reconnoissance, que le seul Discours de feu 

 M. Stenon sur 1' Anatomic du Cerveau, a €ti la source primitive et le modele general de toute 



