Friedrich Wilhelm Nietzsche was a German philosopher, writer, and philologist in the late 19th century whose work has profoundly influenced modern thought. He began his career as a classical philologist at a young age before turning to philosophy. His writing explored philosophical concepts like the Ubermensch and eternal return and critiqued religion, morality, and the "death of God." Nietzsche suffered mental breakdown in 1889 at age 44 and lived his remaining years in an unsound mental state until his death in 1900. His work addressed cultural and philosophical issues through aphorisms and was influential though also controversial.