By the early 16th century there were regular voyages between Lisbon and the Indic. The knowledge of the Atlantic developed by accretion, with the systematic exploration moving into the Indic. The corollary of this activity involved a group of remarkable men established around the academic (mathematician, cosmographer) Pedro Nunes, and the explorer and ‘lead investigator’ João de Castro (navigator, military commander and Vice-Roy of India); such men included Andre de Resende (scholar), João de Barros (chronist and scholar), and possibly Damião de Gois (a diplomat, scholar and friend of Erasmus). The theoretical works of Pedro Nunes (1502-1578) achieved the mathematical determination of the loxodromic curve: the shortest course between two points on the surface of a sphere represented onto a two-dimensional map, clearing the way for the establishment of the Mercator projection. It is Pedro Nunes who states, in his comtemporaneous "Treatise of the Sphere" (1537), that Portuguese navigations were not an adventurous endeavour: