What is its substance and material? And what its causal nature [or form]? And what is it doing in the world? And how long does it subsist?
When thou risest from sleep with reluctance, remember that it is according to thy constitution and according to human nature to perform social acts, but sleeping is common also to irrational animals.
But that which is according to each individual’s nature is also more peculiarly its own, and more suitable to its nature, and indeed also more agreeable.
Constantly and, if it be possible, on the occasion of every impression on the soul, apply to it the principles of Physic, of Ethic, and of Dialectic.
Whatever man thou meetest with, immediately say to thyself:
What opinions has this man about good and bad?
For if with respect to pleasure and pain and the causes of each, and with respect to fame and ignominy, death and life, he has such and such opinions, it will seem nothing wonderful or strange to me, if he does such and such things; and I shall bear in mind that he is compelled to do so.
Remember that as it is a shame to be surprised if the fig-tree produces figs, so it is to be surprised if the world produces such and such things of which it is productive; and for the physician and the helmsman it is a shame to be surprised, if a man has a fever, or if the wind is unfavourable.
Remember that to change thy opinion and to follow him who corrects thy error is as consistent with freedom as it is to persist in thy error.
For it is thy own, the activity which is exerted according to thy own movement and judgement, and indeed according to thy own understanding too.