For forty years our ancestors subsisted on mon. Thereafter things changed. No more mon. Time to don the farmer's overalls and work the land. As the world's economy has developed and changed many have exchanged overalls for business attire and the field for the office. Either way no more free lunches. Or, for that matter, breakfasts and suppers.
This dramatic change speaks for itself. And yet it is very important that we also understand what has not changed.
Rashi (Shemos 16:30) explains
In the days of Yirmiyahu when Yirmiyahu was rebuking them (Bnei Yisrael) "why do you not preoccupy yourself with talmud Torah", and they would say "[if] we neglect our work and preoccupy ourselves with talmud Torah how will we sustain ourselves?" He brought out the jar of mon, [and] said to them ... "your ancestors were sustained with this, the Omnipresent has many messengers to provide sustenance to those who fear Him"
Mon no longer falls from the sky. Now we need to invest effort. That has changed. But our effort is just that and nothing more. Our sustenance, as did the mon, comes wholly from Hakadosh Baruch Hu. In that respect nothing has changed and it never will.
And thus Yirmiyahu hanavi offers a timely and timeless practical lesson in faith. From a secular perspective, arranging a work schedule which allows for regular talmud Torah may disrupt our pursuit of our livelihood. In reality, however, kvi'as ittim laTorah does not interfere with Hakadosh Baruch Hu's ability or plans to provide our sustenance.
The mishna in Shabbos in dealing with the melacha of mechabeh speaks of one who extinguishes a flame k'chas al hashemen etc. He extinguishes the flame because he is concerned not to waste money by needlessly (sic) burning oil. But why the kof ha'dimyon? The Vilan Gaon (ad loc) explains. It is as if he is saving money. In actuality, he is not saving anything. One's sustenance is from Hashem, and surely will not be diminished by shemiras Shabbos.
Mon no longer falls. But things have not changed. Our sustenance comes from Hakadosh Baruch Hu. It may appear tempting to pay cash and avoid sales tax, but are we really saving? A profound, practical, lesson in faith worth remembering an applying, when setting aside time for talmud Torah, contemplating taxes and in many other situations and contexts.