92% sureThese words were traced back to where they first appeared. That source is listed below.
What turned up
Epistulae Morales ad Lucilium, Letter VII; Wikiquote sourced thematic citation.
Sources checked
en.wikiquote.orgChecked using claude-sonnet-5, 20 August 2026Sourced Seneca entry citing Epistulae Ad Lucilium VII
en.wikisource.orgChecked using claude-fable-5, 21 August 2026Epistulae Morales 7.8, Gummere translation (1917) on Wikisource: 'The process is mutual; for men learn while they teach.' — our text is the famous back clause