Complex sentence: At the age of sixteen he was apprenticed to an apothecary, his father's profession, subsequently becoming an apothecary himself, and in 1839, at the age of 20, wrote his first work ("Heinrichs IV. erste Liebe", now lost).
Split into simpler sentences: At the age of sixteen he was apprenticed to an apothecary, his father's profession. He became an apothecary himself, and in 1839, at the age of 20, wrote his first work ("Heinrichs IV. erste Liebe", now lost).