In On First Principles by Origen, how does Origen show that Moses and Jesus' teachings are unique?
Origen (c. 184-254), receiving a philosophical education, was not an ordained Christian minister nevertheless wrote as a theologian and an as a philosopher when he laid out his theological system defining the Christian faith when he wrote De principiis (On First Principles).
One way that Origen shows that Jesus' teachings are unique is by showing that Jesus himself is unique. After first defining the Judaic and Christian God, Origen lays out a logical argument based on a philosophical questioning technique that shows Jesus' relationship to God and proves it to be a unique one. Essentially, Origen shows that God is Spirit, eternal and without beginning, and that God is wisdom and the creative nexus of, the author and originator of the material, the psychological and emotional (soul) and the spiritual elements of the world and existence.
Next Origen shows that Jesus is God's wisdom and the co-creator with God and that, as the co-creative force and wisdom of God, Jesus is also the Word of God and co-eternal with God, as is indicated in the Gospel of John: "In the beginning was the Word, and the Word was with God, and the Word was God" (John 1:1).
He is also styled First-born, as the apostle has declared: "who is the first-born of every creature." The first-born, however, is not by nature a different person from the Wisdom, but one and the same. Finally, the Apostle Paul says that "Christ (is) the power of God and the wisdom of God." (De Principiis, Book I, Chapter 2. On Christ. NewAdvent.com)
By proving the special nature and character of Jesus and by proving his special relationship with God, Origen also proves the uniqueness of his teachings: there are none like him, none can teach like him and none can have or impart the wisdom he possess (because none are of God as he is of God).
One way Origen shows Moses's teachings are unique is to show that his writings were inspired by the Holy Spirit. A second way is to show that the Holy Spirit is unique in the same way Jesus is unique: the Holy Spirit, whose existence cannot be deduced through logical reasoning or by inductive inference, is, like Jesus, co-eternal with God and, while Jesus gives wisdom, the Holy Spirit gives holiness and divine inspiration to those who are rational beings and who are obedient to God's revelation. Moses was one who was rational and obedient, thus he was one to whom the Holy Spirit gave holiness and divine inspiration for writing Scripture.
By proving the special nature of the Holy Spirit and the special relationship between the Holy Spirit and Moses, an obedient servant of God and recipient of Jesus' divine wisdom, Origen proves that Moses's teachings are unique: being rational and the recipient of wisdom, the Holy Spirit's holiness and inspiration produced teachings not replicated anywhere else; they were thus unique.