Career
In 1779 he started another one called Vlijt moeder der Wetenschappen that began to annually announce contests with a prize similar to the Teylers Eerste Genootschap that was founded the year before. In 1782 these two societies were merged and also began to produce plays, which Loosjes wrote, acted, and published himself, becoming a Haarlem bookseller. In the same year January van Walré joined to become an actor, and under his influence, in 1785 the society was reinvented as the theater society Leerzaam vermaak with a strong Patriotic bias with Loosjes and Walré the leaders.
When the House of Orange briefly enjoyed a contrarevolution, Leerzaam vermaak was banned, and Loosjes decided to avoid politics and relinquished his official roles in the group, spending his time on scientific and writing pursuits.
In 1789 he started the Haarlem scientific society Maatschappij tot Nut van "t Algemeen. To continue with his comedies, he began the society Democriet in the same year with the remark Because Heraclitus had to cry, Democritus had to laugh.
In 1790 Walré joined, who again added political color, despite Loosjes" intentions to remain neutral. Loosjes wrote several books and plays, and translated historical works from English into Dutch.