His philosophy books were about Stoicism. These books include his "Letters to Lucilius" and his "Essays" (or ""Dialogues""). Seneca wanted to find the right way for people to be happy, so he wrote about ethics. He believed that some emotions, including anger and grief, are bad and should be avoided. He wrote about the shortness of life, and he wrote about favours, mercy, friendship, and the need to help other people.