Likutei Moharan 19:7/ליקוטי מוהר"ן י״ט:ז׳

17. Now, when someone has the ability to awaken an illumination of the letters of the Act of Creation in each thing, then his eating, drinking and all his [physical] pleasures come only from the illumination of the letters which are in eating and drinking. This corresponds to (Ruth 3:7), “He ate and drank, and his heart was good.” “His LeV (heart) was good” alludes to the illumination of the letters of the L-V (32) times that the Holy Name Elohim appears in the Act of Creation which is in each thing.

2And this is, “His heart was good”—”good” is nothing other than light, as in (Genesis 1:4), “Then God saw that the light was good.” Thus, “He ate and drank, and his heart was good.” His eating and drinking came from a shining and illumination of the letters of the Thirty-two Elohim contained in the meal which he ate.

3And this is, “‘His heart was good’—this is the Grace after Meals” (Ruth Rabbah 5:15). His eating and drinking came from the illumination of the letters that are in the food and drink. This is the concept of Grace after Meals, because food is blessed through the perfection of the Holy Tongue—by causing the letters in each and every thing to be aroused and to shine. It is from there that eating, drinking and the other physical pleasure should primarily come, as explained.