On April 21, 1618 Pedro Paez visited the small spring where the waters of the Blue Nile rise before passing through Lake Tana. The site had been seen before by the military leader of the group of Ethio-Portuguese descendants of the Portuguese soldiers who had helped the Christian kingdom in the wars of 1541-1543, who passed the news to the missionaries shortly before 1607. In both cases the Ethiopian kings, Sarsa Dengel and Susenyos, took them to the sources, showing that the local population had a clear knowledge of the river course. Paez was the first European who described all its characteristics, occupying a complete chapter of his "History of Ethiopia". Although this book was not published until the 20th century, the manuscript was copied and the information was incorporated into the global knowledge before the end of the 17th century, through the works of the German Jesuit Athanasius Kircher and the maps of the Venetian geographer, Vincenzo Coronelli. In this way, a problem that had intrigued travellers, geographers and historians since antiquity was solved. The next European who visited the place was the Scottish James Bruce in 1770, and the sources in Lake Victoria of the other large arm of the river, the White Nile, were not discovered until two and a half centuries later, with the travels of the English John Hanning Speke in 1858-1862.