Responsa for Gittin 121:13

ורמינהו

as it has been taught: Who is an 'am ha-arez? One who does not insist on eating ordinary food in a ritually clean condition.<span class="x" onmousemove="('comment',' Even though he is careful about tithes. ');">²²</span> So R. Meir. The Sages, however, say it is one who does not tithe his produce. But since it says in the later clause of the Mishnah, ONCE SHE HAS POURED WATER OVER THE FLOUR SHE SHOULD NOT TOUCH ANYTHING WITH HER,<span class="x" onmousemove="('comment',' Apparently because the water renders the flour capable of becoming unclean. ');">²³</span> does not this show that the earlier clause<span class="x" onmousemove="('comment',' That she shall not sift etc. ');">²⁴</span> is not speaking of cleanness and uncleanness?<span class="x" onmousemove="('comment',' I.e., that the reason is not anything to do with uncleanness, and must therefore be because of tithe. ');">²⁵</span> — Both the earlier and the later clause speak of cleanness and uncleanness, the former, however, of the uncleanness of ordinary food and the latter of that of the <i>hallah</i>.<span class="x" onmousemove="('comment',' Lit., 'loaf': 'the first of the dough' which had to be offered as a heave-offering. Num. XV, 19. As this was a precept of the Torah, greater care had to be exercised not to assist in its transgression. ');">²⁶</span> The following was adduced in contradiction:<span class="x" onmousemove="('comment',' Of the statement that it is permitted to help an 'am ha-arez to grind. ');">²⁷</span>

Teshuvot Maharam