Law of life - that we must do what nature demands (1.26.1-2)
Whatever is done in accordance with nature is rightly done (1.11.5-6)
In every circumstance I will maintain, the governing part (the authoritative part of the soul - reason) conformable to nature. (1.15.4)
Is it not enough to learn the true nature of good and the evil, and the limits of desires and aversions, and also of the choices and refusuals, and, by employing these as rules, to order the affairs of our life, and dismiss the things that are beyond us? (Fg 1)
