God's knowledge of all things. Revelation discloses that the wisdom of God is without measure (Psalm 146:5). And the Church teaches that his knowledge is infinite.
The primary object of divine cognition is God himself, whom he knows immediately, that is, without any medium by which he apprehends his nature. He knows himself through himself.
The secondary objects of divine knowledge are everything else, namely the purely possible, the real, and the conditionally future. He knows all that is merely possible by what is called the knowledge of simple intelligence. This means that, in comprehending his infinite imitability and his omnipotence, God knows therein the whole sphere of the possible.
He knows all real things in the past, present, and the future by his knowledge of vision. When God, in his self-consciousness, beholds his infinite operative power, he knows therein all that he, as the main effective cause actually comprehends, i.e., all reality. The difference between past, present, and future does not exist for the divine knowledge, since for God all is simultaneously present.
By the same knowledge of vision, God also foresees the future free acts of the rational creatures with infallible certainty. As taught by the Church, "All things are naked and open to His eyes, even those things that will happen through the free actions of creatures" (Denzinger 3003). The future free actions foreseen by God follow infallibly not because God substitutes his will for the free wills of his creatures but because he does not interfere with the freedom that he foresees creatures will exercise. (Etym. Latin omnis, all + scire, to know.)
The short understanding of Omniscience is to have knowledge of all things past,present and future.
Is Mary omniscient (by participation, not by nature)?
Mary is Omniscient by participation and by God's design on the Divine Plan of Man's Salvation.
CCC488 "God sent forth his Son", but to prepare a body for him,125 he wanted the free co-operation of a creature. For this, from all eternity God chose for the mother of his Son a daughter of Israel, a young Jewish woman of Nazareth in Galilee, "a virgin betrothed to a man whose name was Joseph, of the house of David; and the virgin's name was Mary":126
The Father of mercies willed that the Incarnation should be preceded by assent on the part of the predestined mother, so that just as a woman had a share in the coming of death, so also should a woman contribute to the coming of life."
To understand fully the knowledge of God or to become Omniscient in the Divine Plan, one must possessed the Holy Spirit.
1.Mary is Omniscient by Her FIAT to the Will of the Father in his Divine Plan.
Mary's FIAT reveals the Will of the Father.
2.Mary is Omniscient by participation in the Redemptive Mission of Christ.
Mary's gave the Logos Her Immaculate body to accomplished His Redemptive Mission to DWELL with us.
3.Mary is Omniscient by submission to the Salvific Mission of the Holy Spirit
Mary gave Her Sorrowful & Immaculate Heart to the Holy Spirit to INDWELT Her.
4. Jesus uses Mary's Immaculate Body for our Redemption, and the Holy Spirit dwelt in the Her Immaculate Heart to work-out the Salvation of all the Redeeemed.
5. Mary's role and presence is defined from book of Genesis to Revelation.
Genesis3:15 to Revelation 12:1-5
6. God made a Holy Decree a "perennial enmity" between the Woman vs. serpent.(Genesis3:15)
7. Mary is Queen of all things. Sovereign Queen of all the Angels & Saints (CCC966)
CCC966 "Finally the Immaculate Virgin, preserved free from all stain of original sin, when the course of her earthly life was finished, was taken up body and soul into heavenly glory, and exalted by the Lord as Queen over all things, so that she might be the more fully conformed to her Son, the Lord of lords and conqueror of sin and death."508 The Assumption of the Blessed Virgin is a singular participation in her Son's Resurrection and an anticipation of the resurrection of other Christians:
In giving birth you kept your virginity; in your Dormition you did not leave the world, O Mother of God, but were joined to the source of Life. You conceived the living God and, by your prayers, will deliver our souls from death.5
Mary accepted fully the Will of the Father communicated thru the Logos by the Angel Gabriel in the Annunciation;
Lastly, Mary was Omniscient because God crown Her "Sovereign Queen over all things"
The Holy Spirit "Overshadowing at the Annunciation and the Anointing She Received at the Upper Room" made Her Omniscient participation in fullness.
To possessed the Holy Spirit means a share in the knowledge of God.
Mary said "I AM" the Immaculate Conception means Mary's pure soul was prepared by God to received the overflowing graces of God to fulfill Her Role in the the Divine Plan of Man's Salvation.
And in order to fulfill the Divine Plan, Mary was "ANOINTED" to received the graces just like Jesus was "ANOINTED" in eternity to accomplish the Will of the Father. Remember the Name expressed your God given mission, both Jesus & Mary's name was conceived in eternity.That's why Lucifer and his demons must bow down not only in the Name of Jesus but also in the Holy Name of Mary as confessed by demons in Exorcism Rite.(Fr.Amorth and Fr.Bamonte books & testimony)
CCC486 The Father's only Son, conceived as man in the womb of the Virgin Mary, is "Christ", that is to say, anointed by the Holy Spirit, from the beginning of his human existence, though the manifestation of this fact takes place only progressively: to the shepherds, to the magi, to John the Baptist, to the disciples.123 Thus the whole life of Jesus Christ will make manifest "how God anointed Jesus of Nazareth with the Holy Spirit and with power."
The profound mystery of St.Liguori's word pointing to Mary as the "another Advocate" means the Anointing of Holy Spirit would be send to the Mother of the Redeemer for the Salvation of all the Redeemed.
Jesus the Redeemer after He ascended into Heaven will now ask the Father thru His powerful intercession as Mediator to send the Holy Spirit to the Theotokos to 'Anoint" Her as the "another Advocate".
This Wisdom is only grasp by means of Spirit as St.Paul said;
"The person without the Spirit does not accept the things that come from the Spirit of God but considers them foolishness, and cannot understand them because they are discerned only through the Spirit."
Corinthians 2:14 New International Version (NIV)
In closing I will leave the words of St.Faustina;
"Mercy is the flower of Love.
in Love it is conceived, and in deeds it is revealed."
Mary conceived the Love/Jesus and Her Motherly action expressed the Mercy of God, as the Church proclaimed Her Mother of Mercy.
But Mercy is called the flower of Love, what does it mean.
That means we can only ascend and enter God's Kingdom thru God's Mercy and since it a "flower" it mysteriously reveals why the Holy Rosary is a Rose.
The Salvation of man is written in the symbol of a flower, the Holy Rosary is the Mercy of God.
"Sweet Heart of Mary be my salvation" (Pieta Prayer booklet)