The Moral Letters to Lucilius is 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 more than ten years. They are addressed to Lucilius, the then procurator of Sicily, although he is known only through Seneca's writings. Regardless of how Seneca and Lucilius actually corresponded, it is clear that Seneca crafted the letters with a broad readership in mind. The letters often begin with an observation on daily life before proceeding to an issue or principle that is abstracted from it. The result is a diary or handbook of philosophical meditations. The letters focus on many traditional themes of Stoic philosophy such as the contempt of death, the stout-heartedness of the sage, and virtue as the supreme good.