Complex sentence: His grandfather, Georges Sigismond von Bilterlings, (1767-1829), was a Lutheran pastor in Mitau, Courland, today Jelgava in Latvia, a professor, theologian, philosopher and writer.
Split into simpler sentences: His grandfather, Georges Sigismond von Bilterlings, (1767-1829), was a Lutheran pastor in Mitau, Courland, today known as Jelgava, Latvia. He was a professor, theologian, philosopher and writer.