The concept of agency is simply that an agent or representative speaks and acts on full behalf of the one who sent him. This is commonly practiced in modern times in what is known as "the power of attorney". In the Roman world an agent of the Emperor was called the Imperial legate, although the standard usage of the word “legate” today refers to a representative of the Pope. According to the Jewish understanding of agency, the agent was regarded as the person himself. This is explained in The Encyclopedia of the Jewish Religion:
Agent (Heb. Shaliah): The main point of the Jewish law of agency is expressed in the dictum, “a person’s agent is regarded as the person himself”. Therefore, any act committed by a duly appointed agent is regarded as having been committed by the principal, who therefore bears full responsibility for it with consequent complete absence of liability on the part of the agent.
Theophany: (Gk. theophaneia = “appearance of God”), manifestation of deity in sensible form. In the OT, God is depicted appearing as an angel/messenger [Gen 21:17-18], human being [Gen 17:1; 18:3], in natural cataclysms, in a burning bush [Ex 3], a cloud or dream [Gen 28:10-18], or a gentle breeze—forms often associated with the divine “name” or “glory” of God. The mark of biblical theophany is the temporariness and suddenness of the appearance of God, which is here not an enduring presence in a certain place or object.
This is an important biblical phenomenon that foreshadows the coming of Christ. Jesus Christ represented God in a manner that went beyond the way the prophets represented Him. Christ claimed to act in God’s stead in a way that the prophets never said that they did:
“I always do what pleases Him” (John 8:29)As the naturally created Son, Christ spoke as one who knew God and His will intimately, through a unique personal acquaintance [Luc 24:39; Jn 20:27; 1 Jn 1:1-4]. Also see monogenes.
“I do exactly what my Father has commanded me” (John 14:31)