The Moral Letter to Lucilius are a collection of 124 letters which were written by Seneca the Younger at the end of his life, during his retirement, and written after he had worked for the Emperor Nero for fifteen years. (These Moral Letters are the same letters which Tim Ferriss promotes in the Tao of Seneca).
Lucius Annaeus Seneca (often known simply as Seneca or Seneca the Younger); ca. 4 BC – 65 AD) was a Roman Stoic philosopher, statesman, and dramatist of the Silver Age of Latin literature. He was tutor and later advisor to emperor Nero, who later forced him to commit suicide for alleged complicity in the Pisonian conspiracy to have him assassinated.