"OUR wall is secure, we have provisions for a very long time, and every other preparation." These are what render a city fortified and impregnable, but nothing but its principles render the human soul so. For what wall is so strong, what body so impenetrable, or what possession so unalienable, or what dignity so secured against stratagems? All things else, everywhere else, are mortal, easily reduced; and whoever in any degree fixes his mind upon them, must necessarily be subject to perturbation, despair, terrors, lamentations, disappointed desires, and incurred aversions.
EPICTETUS. DISCOURSES. Book iv. §5. ¶3.
THE things or objects themselves, reach not unto the soul, but stand without still, and quiet, and that it is from the opinion only which is within, that all the tumult and all the trouble doth proceed.
MARCUS AURELIUS. MEDITATIONS. Book iv. 3.