 He suffered from health problems and bodily swellings, which obliged him to retire to the Jesuit ranch of Chicomocelo, where he devoted himself to writing and botany until his death in 1764.As a historian, he was cautious in his investigations, critical in his selection of sources and concerned with discovering the truth.In his major work on California, he cited Georg Marcgraf and Willem Piso's "Historia Naturalis Brasiliae" (1648), an important compendium on flora and fauna in Brazil, which circulated widely in northern Europe and beyond.