He grew up in Amersfoort where his father was a minister. Around 1586 he settled in Amsterdam being a schoolmaster. Because he had a special gift for mathematics and astronomy he attracted a special kind of trainees: seamen who wanted to know how to sail the world. This way he was vital in the education of some of the famous and important Dutch seafarers like Cornelis Houtman (who discovered a new sea route from Europe to Indonesia and managed to begin the Dutch spice trade) and Jacob van Heemskerck (who attempted to discover an Arctic passage from Europe to China. He also provided them with the necessary maps and instruments. He teached nautical techniques for 25 years in Amsterdam, and he created a song which could be used to determine the position of the ship based on the observed position of the stars.
In 1593 he published a book containing a treatise on the Jewish calendar and chronology, combined with poems and a song-book (see the pictures below). He wrote many religious pamphlets, promoting religious tolerance and freedom of conscience. In the age of many religious conflicts he called himself a ‘Neutralist’, saying: "The church of Christ is a majestic cathedral with many doors, all leading to the center," with this metaphor expressing his idea that one church is as good as another. This attitude resulted in many enemies, and finally he had to leave Amsterdam in 1611. He moved to Hoorn and became a brandy salesman.