This analogy of the yetzer hara being an enemy that attacks us endlessly is perfect. We do not always view the yetzer hara as such an evil foe, but indeed it is. It tries to find all the weaknesses in our character and use those against us. But here's the catch: if we let it. We are partners in this battle and it is possible to be victorious if we fortify ourselves and set up barriers. And no other barrier is more effective than wisdom itself; that is, wisdom from the Eternal.
a wall as strong as your mind
There was a little city, and few men in it; and there came a great king against it, and besieged it, and built great siege works against it; and a poor wise man was found in it, and he by his wisdom delivered the city; yet no man remembered that poor man. And said I, "Wisdom is better than might; but the poor man's wisdom is despised, and his words are not heard." — Ecclesiastes 9:14-16
In Duties of the Heart, Rabbi Paquda uses this example above to show that wisdom alone defeats the great king [the evil inclination]. There is much symbolism that he explains in this example. He shows that the human being is represented by a "little city". The reference to "few men" has to do with the limbs and faculties of the soul, as they appear to be limited compared to the inclinations of the heart. The "great siege works" that the great king hurls at the little city are none other than evil imaginings, thoughts and anything else that would seek to destroy the soul.
But then, we have the poor wise man. Why is he considered poor? Rabbi Paquda says that he is thought of this way because he doesn't have a multitude of followers. We read on to find that his wisdom is spurned. It isn't popular, fashionable, chic, burly. Forget that the man saved the city. Who cares if he rose up with what seemed like limited resources and defeated the great king? Wisdom just isn't a hip thing to have. Or is it? Truly, the wisdom that this poor man offered up separated good from evil by vanquishing the evil. There is power to be had in godly wisdom.
so sure of yourself that you cease to exist
Rabbi Paquda urges us in the chapter to be on guard, to separate ourselves from evil through vigilance and vigor. He implies that the use of heavenly wisdom can separate us from evil. He suggests that we can draw inspiration from this story to stand up to our lowly instincts with intellect as a shield. As it says, "The evil bow low before the good" (Proverbs 14:19).
As we are drawing close to end of a cycle of 13-week Mussar practice, we have to ask ourselves: have we been vigilant in setting up barriers, in using the wisdom of a Mussar practice to work on defeating the great king? Are we so certain that we don't need extra wisdom, protection and an honest eye on ourselves to make sure our little cities aren't vanquished? When we become so certain that we don't need to be on guard, it is then that we become weakened and set ourselves up for failure. If we are to be true followers of Mashiach Yeshua, then we need to be constantly looking within, never truly sure of ourselves until the day that we die. Only then are we being wise talmidim and living up to the calling of being holy as Hashem is holy.