Seneca’s hint at the format of his letters

Started reading Seneca’s Letter XXVII: On The Good Which Abides, and I was struck by the opening paragraph. It’s a hint at the format of his Epistulae, which are basically a series of letters to himself (hypomnemata), with the reader as his audience. He’s not giving advice to others, but he’s sharing his thoughts, and he’s having it out with himself, merely making use of Lucilius as his pretext.