Together with various other forbidden practices, the Torah admonishes, “Do not eat the blood” (Lev. 19:26). Literally, the verse reads, ‘Do not eat over the blood.’ What does it mean to ‘eat over blood’?
The Talmud offers several explanations, including the warning, ‘Do not eat before you have prayed over your blood [i.e., for the sake of your soul]’ (Berachot 10b). Why is it so important to refrain from eating before reciting the morning prayers?
We find that the Torah equates blood to the nefesh (the soul), as it says, ‘The blood is the nefesh’ (Deut. 12:23). What is the nefesh? This is the lowest part of the soul, the basic life-force that is common to both humans and animals. The desires of the nefesh naturally relate to our physical needs. However, the human intellect can guide and direct these desires. In fact, this is the function of prayer: to refine and elevate the emotional and imaginative parts of the soul. Through prayer, we bind our feelings and desires to pure and holy aims.
On this basic level, what we do in the beginning of the day sets the tone for the entire day. Our initial feelings and impressions accompany us throughout the day.
If we start the day by eating, then we have already weighed down our souls with the burden of satisfying physical wants. This establishes the desires of the nefesh as base and animalistic.
But if the very first act of the day is prayer, then we have ensured that the initial impressions on the soul will be pure, directed towards higher and holier aspirations. While the day is fresh and the soul has not been burdened with lowly images, prayer can make its impact, impressing upon the soul the sublime goal of drawing close to our Creator.
(Gold from the Land of Israel, pp. 205-206. Adapted from Olat Re’iyah vol. I, p. 248; Ein Eyah vol. I, p. 61)