Editing Jan Oort (section)

=== Nazi invasion of Netherlands ===
In 1940, [[Nazi Germany]] [[Battle of the Netherlands|invaded the Netherlands]]. Soon after, the [[Reichskommissariat Niederlande|occupying regime]] dismissed all Jewish professors from [[Leiden University]] and other universities. "Among the professors who were dismissed", Oort later recalled, "was a very famous … professor of law by the name of Meyers. On the day when he got the letter from the authorities that he could no longer teach his classes, the dean of the faculty of law went into his class … and delivered a speech in which he started by saying, 'I won't talk about his dismissal and I shall leave the people who did this, below us, but will concentrate on the greatness of the man dismissed by our aggressors.'"<ref name= OHT />

This speech (26 November 1940) made such an impression on all his students that on leaving the auditorium they defiantly sang the [[Wilhelmus|anthem of the Netherlands]] and went on strike. Oort was present for the lecture and was greatly impressed. This occasion formed the beginning of the active resistance in Holland. The speech by [[Rudolph Cleveringa]], the dean of the faculty of Law and former graduate student of professor Meijers, was widely circulated during the rest of the war by the resistance groups. Oort was in a little group of professors in Leiden who came together regularly and discussed the problems the university faced in view of the German occupation. Most of the members of this group were put in hostage camps soon after the speech by Cleveringa. Oort refused to collaborate with the occupiers, "and so we went down to live in the [[Rural area|country]] for the rest of the war." Resigning from the Royal Academy, from his professorial post at Leiden, and from his position at the Observatory, Oort took his family to Hulshorst, a quiet village in the province of [[Gelderland]], where they sat out the war. In Hulshorst, he began writing a book on stellar dynamics.<ref name= NYT /><ref name= OHT />