Starting from the Top
Condensed from Ein Ayah, Shabbat 9:77
Gemara: "Like a tapuach (which may or may not be an apple tree, and it is not clear which variety) among the trees of the forest, so is my beloved among the young men …" (Shir Hashirim 2:3). Why is Israel compared to an apple tree? It is to teach you that just as an apple tree has its fruit begin to grow before its leaves, so too Israel said "we will do" before "we will hear."
Ein Ayah: Lower levels in the realm of the physical and spiritual are arranged opposite the higher levels in two manners.
Sometimes higher levels develop through the lower levels, which requires the latter to exist before the former. There are also times that the higher levels appear from the fundamental light, without need to be preceded by the more basic levels. Even in that case, the lower levels are important, and they come along and protect and strengthen the higher levels and allow for connections between practical life and the higher levels.
Proper actions make up the upper portion of the spiritual apparatus and are the manifestation of the Torah within life, leaving its insignia of sanctity on the world. It is not that the actions remind us of some idea to recognize and remember. Rather, proper actions are the high content according to the way Hashem set the world. They become partners in Creation and improve existence. This is the special ability Israel was given by receiving a Torah full of holy actions that exceed any halachic or moral ideas alone.
The higher "fruit" do not come from the levels beneath them, even the highest preparatory level, which is hearing. This is the idea of the fruit coming before the leaves. From the idea of basing the existence on the source of the life of the world, there also flows a light of wisdom that includes hearing and listening. This adorns, strengthens, and broadens the revelation of the higher level of action, even though they come afterward. That is how Israel resembles the apple tree.
Natural Spiritual Simplicity
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.