"My third maxim was to endeavor always to conquer myself rather than fortune, and change my desires rather than the order of the world, and in general, to accustom myself to the persuasion that, except our own thoughts, there is nothing absolutely in our power. ... This single principle seemed to me sufficient to prevent me from desiring for the future anything which I could not obtain, and thus render me contented. ... But I confess there is need of prolonged discipline and frequently repeated meditation to accustom the mind to view all objects in this light; and I believe that in this chiefly consisted the secret of the power of such philosophers as in former times were enabled to rise superior to the influence of fortune, and, amid suffering and poverty, enjoy a happiness which their gods might have envied."