The Gnosis is to receive the spirit of wisdom that gives us the eternal life, we are infused by Charity to be teachers or doctors in the science of Wisdom, the science of God. We need the soul to live but the spirit to judge the eternal and immutable truths, the Gnosis is the access to the plane of the truth.
The prophet Daniel in the Old Testament is an example of the man enlightened by the Gnosis: Daniel is a clairvoyant, that is to say an oracle, interprets in the occult of God and has the discernment and the science of the divine; King Balthazar, son of Nebuchadnezzar, refers to Daniel: "I have heard that the spirit of the gods is in you and that you have insight, intelligence and outstanding wisdom" Book of Daniel 5:14.
Daniel interprets the dreams of the king Nebuchadnezzar, Book of Daniel 2:31-45 and 4:7-15, also Daniel interprets the vision of Balthazar in the Book of Daniel 5: 5-9. Daniel finally has prophetic visions similar the Apostle John in the Book of Revelation.
Also Joseph, the son of Jacob in the Book of Genesis who interprets the dreams of the Pharaoh (Genesis 41: 14-36) who acts as oracle and clairvoyant, is another case of a person gifted by the Gnosis.
Gnosis is fundamentally the resolution of an inner conflict between the nature of the world and the spiritual nature. In fact Jesus talks about the Gnosis in the Gospel of John: "Very trully, I tell you, no one can see the kingdom of God unless they are born again. How can someone be born when they are old? Nicodemus asked. Can he enter a second time into his mother's womb to be born? John 3:3-4.
For the natural man, the Gnosis is incomprehensible because it is an infusion, a spillover from the high as in Pentecost 2:1: "When the day of Pentecost came, they were all together in one place. Suddenly a sound like the blowing of a violent wind came from heaven and filled the whole house where they were sitting. They saw what  seemed to be tongues of fire that separated and came the rest on each of them. All of them were filled with the Holy Spirit."
St. Augustine tells us his spiritual illumination in the Book Confessions: "I said these things and I cried with bitter contrition in my heart, but I heard a voice from a neighboring house, like a boy or a girl saying:" Take and read, take and read "... I did not want to read more, nor was it necessary either, because to the point that I ended the sentence, as if a secure  light had infiltrated my heart, all the darkness of my doubts dissipated", Book VIII, C 12, Confessions.