Musar על ברכות 27:23

The Zohar also explains that the last part of the metaphors in the verse refers to the 4 חיות Ezekiel saw in his vision of the מרכבה, and Rekanati page 109 comments on that. He says that every concept can be described by means of some metaphor, example. The relation of the metaphor to the concept it represents is like that of the shadow to the object that casts it, from which it is inseparable. The life-force, רוח of the beast which serves as the offering is derived from the שור, ox, of the four חיות in Ezekiel's vision. When the animal rises in the form of smoke after being offered on the altar it re-unites with its source in the מרכבה, G–d's celestial chariot. The life-force of the bird which serves as an offering similarly re-unites with the חיה called eagle in Ezekiel's vision of the מרכבה. The פני אדם, a third category of the four חיות which form part of Ezekiel's vision, derives "nourishment" i.e. is re-united when man on earth initiates the bringing of sacrifices involving his own נפש ונשמה. Each category of the מרכבה, the carrier of G–d's throne in Ezekiel's vision, unites with its respective counterpart on earth. Only afterwards are they able to accept a gift from the "King." Prior to such development no one has the right to enjoy the "king's" meal. This is what our sages (Berachot 14a) had in mind when they said that one must not engage in one's own mundane activities before one has offered prayer to G–d. The fourth חיה, the image of the lion in Ezekiel's vision, does not confer of its strength to others but is only a passive recipient. When Israel was at its optimum spiritual level, they lay on the altar. This is an allusion to the lion which does not have to rouse itself.