For Cheshbon was the city of Sichon, king of the Amorites, and he had fought against the first king of Moab, taking all his land from his possession, as far as Arnon. Concerning this, those who speak in parables say, “Come to Cheshbon, may it be built and established as the city of Sichon. For fire went forth from Cheshbon, a flame from the city of Sichon; it consumed Ar of Moab, the masters of the high places of Arnon. (Bamidbar 21:26-28)
Besides being a description of an historic event the Torah is hinting here in coded language about a valuable strategy for success in this world on the way to the next. In a cryptic way this is how the Talmud breaks it down: Rabbi Shmuel bar Naḥman says that Rabbi Yoḥanan says: What is the meaning of that which is written: “Therefore they that speak in parables [Hamoshlim] say: Come to Cheshbon! Let the city [ir] of Sichon be built and established! For a fire is gone out of Cheshbon, a flame from the city of Sichon; it has devoured Ar of Moab, the lords of the high places of Arnon” (Numbers 21:27–28)? The Gemara interprets these verses homiletically.
“Hamoshlim”; these are the people who rule over [Hamoshlim] their evil inclination. They will say: “Come to Cheshbon,” meaning: Come and let us calculate the account of [Cḥeshbono] the world, i.e., the financial loss incurred by the fulfillment of a Mitzva in contrast to its reward, and the reward for committing a transgression, i.e., the pleasure and gain received, in contrast to the loss it entails. (Bava Basra 78B)
What is this great advice? Take advice from those who have been victorious in their personal battle against their negative inclination. They are in the best position to give council. They have a track record of success and they see the field better than the un- and under-initiated. The Mesilas Yesharim describes a garden maze with a labyrinth of confusing walls. Only the one who has made it to the top can see where which path leads to progress and which lead to a dead end. From his perspective everything is clear.
Secondly those people who championed the gauntlet of life have one clear piece of guidance. Make a calculation! Before any act, pause and make a simple cost benefit analysis. Weigh the benefit of sin versus the cost and the benefit of the Mitzvah against the cost and everything will be clear as day.
Let us say that someone is about to yield to the temptation to eat a cheeseburger. He thinks for a moment and considers how long the pleasure of that meal will last and what will become of it after the few moments of delight have passed his digestive system. Then he measures that in proportion to the giant stain he is creating on his eternal garment. As soon as the calculation is completed the mind is convinced that a moment of pleasure versus never-ending embarrassment might bit a bit too costly to justify. One who yields impulsively is obviously not in the habit of making that calculation.
Here’s a more subtle example. When I was purchasing Tefillin for my oldest son before his Bar Mitzvah, I was in touch with a Sofer in Israel. We were planning to go to Israel and have him put them on for the first time 30 days before his 13th birthday and to keep the interest high I kept him in the loop with updates about his Tefillin’s progress. One time the Sofer called and asking if I want some extra feature that added a certain Hallachic beauty to the Tefillin and the differential in price would be $125. Instead of the Tefillin costing $1,250.00 it would be $1,350.00. My son asked me nervously which one I opted for and I told him that we are going for the 1350. He nodded in excitement although neither of us appreciated about the value of the upgrade.
My wife had a different take initially. Why spend an extra $125.00? I explained that he will be wearing those Tefillin for the next 80 years, six days a week, 50 weeks a year. Do the math! $125 divided by 24,000 equals $.005 that is 1/20 of a penny a day per use. Then there’s the factor of the smile of recognition on his face. He got the implied message! It was a lesson for all time! He was left with a lasting impression that yes Mitzvos are worth the price.