On Old Age (Latin De Senectute or Cato Maior de Senectute) is a dialogue by Cicero, written about 44 BC, and set a century earlier. The aged Cato the Censor is portrayed in discussion with the younger Scipio Aemilianus and Laelius, expounding his views on dealing with old age, and his belief in the immortality of the soul. The early part of the dialogue is influenced by Plato's portrayal of Cephalus in Book 1 of The Republic.
On Old Age at Amazon: United States.
Free online texts
Gutenberg: Cato Maior de Senectute. Latin text, multiple formats.
Gutenberg: Treatises on Friendship and Old Age by Marcus Tullius Cicero, translated by Evelyn Shuckburgh. Multiple formats.
LacusCurtius: Cicero on Old Age, translated by W.A. Falconer (1923). HTML format.
Latin Library: Cato Maior de Senectute. Latin text, HTML format.
Perseus: De Senectute. Latin text, HTML and XML formats.
Perseus: Cato the Elder On Old Age, translated by W.A. Falconer. HTML and XML formats.
Wikisource: Cato Maior de Senectute. Latin text, multiple formats.
Wikisource: De Senectute, translated by Andrew P. Peabody (1884). Multiple formats.
History of Philosophy without any gaps: Rhetorical Questions: Cicero - podcast by philosopher Peter Adamson.
History of Philosophy without any gaps: Raphael Woolf on Cicero - podcast by philosopher Peter Adamson.
Internet Encyclopedia of Philosophy: Cicero.
Librivox: On Old Age, public domain audiobook.
The Great Conversation: Further reading at Tom's Learning Notes
Plato: The Republic.
Latin resources: Learn to read Latin texts in the original.