Willem Blaeu was the founder of the Blaeu cartographic dynasty, the finest mapmakers of the Golden Age of Dutch cartography. He studied astronomy and instrument making under Tycho Brahe in his tower at Uranienborg in 1594, before moving to Amsterdam. He eventually established his own shop in 1605, close to his contemporaries and rivals Johannes Janssonius and Jacob Colom. He was granted a privilege to print a navigational guide in 1606. Two years later, he produced a set of large carte-à-figure wall maps of the four continents and published Het Licht der Zeevaerdt, a traditional oblong format pilot with coastal profiles to accompany the sailing instructions. The book was popular enough for Janssonius to publish a pirated version in 1620. Blaeu responded by issuing the Zeespiegel in 1623, an enlarged and improved version of his earlier work. The Zeespiegel also sold well, but Blaeu could not afford to rest on his laurels; Jacob Colom produced a cheap and accurate challenger, De Vyerighe Colom (1632). Blaeu’s parting shot was the Havenwyser van de oostersche in 1634, an amalgamation of his previous work, but it was prone to the same errors it singled out in its competitors.