A record which finds general acceptance tells us that Willem Blaeu was born in the village of Alkmaar in the year 1571.[20] Of his childhood years very little is known. It was some time in his early boyhood that he went to Amsterdam, where he found employment, it appears, at first in the house of a Holland merchant, and later as a joiner’s apprentice. We can be certain neither of the time when he decided to leave Amsterdam, nor of the exact circumstances which induced him to visit the island of Hveen, then belonging to Denmark, an event of much significance in his life. We, however, cannot be far wrong in asserting the promptings for this visit to have been his early liking for mathematical, geographical, and astronomical studies. It was here that he first came into intimate relations with Tycho Brahe, the famous Danish astronomer, who, in the year 1576, through princely favor, came into possession of this island, and, as before noted, had erected here his remarkably well-appointed astronomical observatory, which he called Uranienburg.[21] For nearly a quarter of a century this was one of the most famous centers in all Europe for the study of astronomical science and of its practical application. Blaeu, however, was not the first of the young Netherlanders to find the way to Uranienburg to receive instruction from the great master.[22] Of his sojourn on the island we have but little direct information. It appears certain that he passed at least two years with Tycho, engaged the while in study and in the construction of mathematical and astronomical instruments. That the relations between the two distinguished scientists continued to be of the most friendly character after Blaeu returned to Amsterdam is very certain. Not a few of those who in later years praised Blaeu’s scientific attainments refer to him as “the pupil and longtime friend of Brahe,” and Blaeu himself, in certain legends appearing on his globes and maps, refers to him as his teacher. It cannot be doubted that Blaeu owed to his abode on the Island of Hveen the real foundation of his scientific knowledge, both in the field of geography and astronomy, as well as his knowledge of the construction and the skilful use of mathematical instruments. We have reason for believing that a number of the instruments which served the great astronomer in his investigations[23] were the work of Blaeu, and it is an interesting fact, as we know, that Brahe’s observations, here made, formed the basis for Kepler’s calculations, leading him to the discovery of the laws which immortalized his name.[24]