Accordingly, in May 1617, Descartes set out for the Netherlands and took service in the army of Prince Maurice of Orange.
In 1636 Descartes had resolved to publish some specimens of the fruits of his method, and some general observations on its 7 lb.
In 1644 it appeared in a Latin version, revised by Descartes, as Specimina philosophica.
The dispute on the latter point between Fermat and Descartes was continued, even after the philosopher's death, as late as 1662.
Only survived five years at Utrecht, and it was reserved for Heinrich Regius (van Roy) - who in 1638 had been appointed to the new chair of botany and theoretical medicine at Utrecht, and who visited Descartes at Egmond in order more thoroughly to learn his views - to throw down the gauntlet to the adherents of the old methods.