Between May 1875 and December 1879, Vincent van Gogh's life was marked by a devout evangelical piety, distinctly different from what had gone before. Although raised in a religious family, his father a Dutch Reformed minister in the Groningen tradition, van Gogh barely mentions religion in his early letters. His religious fervor deepened considerably, however, sometime during 1875, while he was living in Paris. Van Gogh's letters dating from May 1875 are increasingly filled with biblical quotations and religious reflections. His sister-in-law, Jo van Gogh-Bonger, in describing van Gogh's character during this period wrote, “that was Vincent's aim—to humble himself, to forget himself, ‘mourir à soi-meme,’ (to sacrifice every personal desire), that was the ideal he tried to reach as long as he sought his refuge in religion, and he never did a thing by halves.”