Book III

Marcus argues that one must hasten to use reason and fulfill duties because both death approaches daily and intellectual faculties naturally decay with age, potentially failing before death.

Marcus contends that all natural phenomena—even those seeming flawed or decayed—possess inherent beauty and delightfulness when properly contemplated by the disciplined mind.

Marcus catalogs the deaths of famous physicians, astrologers, conquerers, and philosophers to illustrate that even the greatest and wisest eventually die, and that death offers release from pain or continued service.

Marcus urges the reader to cease thinking about what others do, say, or think, except when it serves the common good, to preserve the rational faculty and maintain a clear, virtuous mind.

Marcus prescribes that one should act only with will and reason, avoid pretension, and remain steadfast in virtue—like a soldier awaiting the signal to depart life.

Marcus advocates for cheerfulness and independence that comes naturally from disciplined character rather than dependence on external help or tranquility from others.

Marcus argues that righteousness, truth, temperance, and fortitude—and a mind accepting what reason and providence dictate—should be preferred above all external goods, to which one must not yield.

Marcus insists that nothing profitable is worth gaining if it requires breaking faith, losing modesty, or other vices; the truly virtuous person lives without desire or fear and is ready for death.

Marcus describes the truly disciplined mind as free from foulness, servility, malice, and concealment, living so virtuously that death cannot surprise it as incomplete.

Marcus emphasizes that one must guard the faculty of judgment so it aligns with nature and rational constitution, and focus only on the present moment, recognizing past and future as insignificant.

Marcus recommends constantly analyzing what presents itself to the mind by breaking it into parts, using proper names, and understanding its utility and place in the universe and human life.

Marcus instructs the reader to ask which virtue applies to one's immediate situation and to trace all events to God, fate, or one's neighbor, responding with justice and kindness.

Marcus asserts that by attending to the present with reason, keeping one's spirit pure, and cleaving to truth without hope or fear, one achieves happiness that no one can hinder.

Marcus compares virtue to having instruments always ready and insists that one must keep ready knowledge of both divine and human matters, understanding their mutual relation.

Marcus cautions that one will likely not live long enough to enjoy retirement reading commentaries and thus should hasten to act virtuously in the present while one can.

Marcus distinguishes that senses belong to the body, desires to the soul, and rational principles (dogmata) to the intellect, each with its proper function.

Marcus defines the unique virtue of human beings as willingly accepting what is destined while keeping the rational spirit pure, truthful, and just—what distinguishes humans from beasts and tyrants.