Bringing the blood of a sacrifice to the altar marks the climax of the atonement process, a moment when the life force of the animal is elevated and sanctified. While the instructions are given as a general guide, the actual physical task is carried out specifically by the priest, one of Aaron's sons [אבן עזרא]. The procedure requires absolute precision. The primary approach among commentators is that the blood must be placed exactly and high up on the horns of the altar. This stands in sharp contrast to other offerings, where blood is simply thrown from a distance against the lower portion of the altar wall. Applying the blood directly with a finger onto the four distinct horns carries deep significance. It serves to atone for severe sins rooted in the four material elements of the world, challenging a person to abandon physical desires that ultimately fade away [רלב״ג]. Spiritually, the blood represents the very essence of the animal's life. By placing it high upon the horns, the priest symbolizes the upward direction of life, reflecting an earthly existence that constantly strives to elevate itself toward God [רש״ר הירש].
After the horns are anointed, the remaining blood left in the vessel is poured out at the base of the altar. Commentators agree that the instruction to pour the entirety of the blood refers only to this leftover amount, not the original total. This base is described as a protruding receptacle that surrounds the altar at the height of one cubit from the ground [רש״י]. A fascinating discussion arises regarding the exact shape of this base. Some commentators envision the massive stone altar built much later in the Temple, which featured an inward indentation that formed a stepped foundation [מזרחי, שפתי חכמים, גור אריה]. Others, however, emphasize that the original instructions refer specifically to the hollow copper altar constructed by Moses in the wilderness. In that structure, the base was an actual copper ledge, resembling a pipe that wrapped completely around the altar [משכיל לדוד].
The pouring of this remaining blood takes place specifically at the southwestern corner of the base. Because this corner faces the Holy of Holies, it serves as a powerful reminder to direct all physical and material actions entirely toward the service of God [רלב״ג]. Furthermore, pouring the blood at the foundation symbolizes planting the essence of life firmly into the ground and the foundational values of the Torah's sanctuary [רש״ר הירש]. Beyond these symbolic layers, the act served a clear educational purpose. By having the altar symbolically consume and destroy the blood, it helped distance the Israelites from the widespread ancient practice of eating blood themselves [רלב״ג]. The absolute necessity of both the horns and the base is legally binding, and a physical flaw in either component invalidates the entire altar [תורה תמימה].
On a deeper, hidden level, the entire sacrificial system, including the handling of the blood and the burning of the fats, is designed to draw down spiritual abundance and unite heavenly forces. Human sin typically begins with thoughts and schemes, which are traditionally associated with the kidneys, and is carried out through material desires, linked to the liver and the fat. Therefore, the blood, representing the soul, is offered alongside these specific internal organs. They are sacrificed together to achieve atonement for the exact physical and mental forces within the person that originally agreed to and participated in the sin [רקנאטי].