Probably written several years before the Consolatio ad Polybium and the Ad Helviam matrem, Seneca’s Ad Marciam is addressed to the daughter of the famous historian Aulus Cremutius Cordus, in order to relieve the grief caused by the death of her son Metilius. To achieve this goal, Seneca makes use of rhetorical as well as philosophical arguments. Above all, he draws on the repertoire of Stoic paradoxes (e.g., the idea of life as an indifferent external element which should be considered neither a good nor a bad thing per se).
At any rate, whereas the structure of the final section of the treatise that includes an artistic depiction of a life-after-death setting reminds of Cicero’s …
Li Causi, Pietro. "De Consolatione ad Marciam". The Literary Encyclopedia. First published 20 October 2015
[https://www.litencyc.com/php/sworks.php?rec=true&UID=35607, accessed 22 February 2019.]