(condensed from Ein Ayah, Shabbat 9:78)

Gemara: A heretic saw that Rav was involved in halachic research and had his toe under his foot, pressing it until it bled. He said: You are a hasty nation, who put your mouth before your ears (i.e., said “We will do and hear”), and you continue with your hastiness. First you should have heard; if you could accept it, you would accept it; if not, you would not accept it. Rav answered: For us, for whom it was enough to go on trust, the pasuk says: “The simplicity of the upright guides them” (Mishlei 11:3). About those people who prefer tricks, it says: “The deviousness of the unfaithful will devastate them” (ibid.).

Ein Ayah: When one sees the highest focus on the spiritual overcome all of the physical feelings, to the point that it cancels them out, he can view that show of strength in two ways. It could be a foreign matter that breaks the natural manner of a person’s life. If so, one should be careful that it not go beyond a reasonable degree, so that it not ruin his physical life. The other way is for the spiritual to complete the physical, so that the physical joins in with the spiritual and in that way loses its separate identity. In such a healthy manner, life is safe from related dangers. To the contrary, it must, by nature, add strength by returning the physical to its foundation and source.

Upright people feel that their natures are supplemented by increased spirituality, which comes from the sanctity of Torah in its highest form. That is why the simplicity of being accepting is a guide. Those who are repelled by such a nature, which could have been in their souls, are like those who betray the potential to be upright.