The soul is made like to God by grace. Hence for a divine person to be sent to anyone by grace, there must needs be a likening of the soul to the divine person Who is sent, by some gift of grace. Because the Holy Ghost is Love, the soul is assimilated to the Holy Ghost by the gift of charity: hence the mission of the Holy Ghost is according to the mode of charity. Whereas the Son is the Word, not any sort of word, but one Who breathes forth Love. Hence Augustine says (De Trin. ix 10): "The Word we speak of is knowledge with love." Thus the Son is sent not in accordance with every and any kind of intellectual perfection, but according to the intellectual illumination, which breaks forth into the affection of love, as is said (John 6:45): "Everyone that hath heard from the Father and hath learned, cometh to Me," and (Psalm 38:4): "In my meditation a fire shall flame forth." Thus Augustine plainly says (De Trin. iv, 20): "The Son is sent, whenever He is known and perceived by anyone." Now perception implies a certain experimental knowledge; and this is properly called wisdom [sapientia], as it were a sweet knowledge [sapida scientia], according to Sirach 6:23: "The wisdom of doctrine is according to her name." (Summa Theologiae, Ia, q. 43, a. 5, ad 2. Trans. English Dominicans)
The soul is assimilated--made similar--to the Holy Spirit by charity, and made similar to the Son by "the intellectual illumination which breaks forth into the affection of love." The true perception of God--we would probably say 'experience' where Thomas says "experimental knowledge"--is thus a con-formity to the processions of the Word and Spirit in God, a loving knowledge or a recognizing love according to the Son and the Spirit Who are missisoned to the soul.
As the Word of God proceeds in God as God's own perfect self-knowledge and self-illumination, and as the Spirit proceeds as the Love that is the shared principle of these two moments, so the soul is assimilated to God by a loving Knowledge, a recognizing Love.
Today I was just reflecting on how prayer could be simply defined as a making of space, both inside and out, so that this 'experimental knowledge' can be noticed. We find a quiet time of the day. We seek a prayerful place. We practice whatever works for us in the letting go of the stream of thoughts and emotional charges that we superficially think of as our selves. All of this ascesis serves the simple purpose of helping us to notice the loving desire for God within. To notice it is to know it, and we find ourselves touching our true happiness and destiny: the loving knowledge of God.
St. Thomas reminds us that this experience of noticing the loving desire for God within is not something we are 'doing,' as if prayer were one more task during the day. In fact, to notice the loving desire for God is to become aware of the Son and the Spirit having become newly present in us, assimilating our minds and hearts to the perfectly delighted love and knowledge we call God. In other words, the loving knowledge of God within us, no matter how obscure and incomplete, is the Son of God having been missioned into our soul.
This loving Knowledge we call Wisdom, and prayer is our chance to taste the Tasty Wisdom that is the mission of the divine persons in us.