Question: “In your diagram, what do you mean by “culturally” ready to absorb our humanity?”
Answer: When I do mention this expression, I am speaking about the time when Jesus starts His Mission, at the age of 30. He is first Baptised. Here is how I did put it in the Diagram: Baptism of Christ: at the age of 30 (see Luke 3:23), He starts His ministry. Christ is ready to receive us in Him. The Sponge is culturally and humanly ready to absorb our humanity.”
As I did mention in “The Spiritual Journey 2”, Jesus grows, in His human nature, as saint Luke says: “And Jesus grew in wisdom and stature, and in favour with God and men” (Luke 2:52). His Divine Nature doesn’t grow, doesn’t require any growth.
To Save us “out of love”
Since God wants to save us with His human nature, considering His Human Nature as a noble living “tool”* we need to pay attention to the way God does it.
*”tool”: first, let us not be offended by the expression “tool”. It has to be taken and understood and an image, and only taking part of the similarity not all of it. Because a normal “tool” we use in our daily life is rather a “dead” one. While we can’t say that about the “human nature” that the Son of God takes. It is alive. A body, a soul and the highest part of the soul: the spirit, are very alive, they have their functions, and their relative autonomy according to their very nature. They are called here “tool” only in a analogical way. They have their total and full dignity. So let us not take the negative aspect of the image.
It would have been much “easier” for God to save us with his Divine Nature alone, but this wouldn’t be an “out of love” way to save us, it would have been “out of power”. Love makes the one who loves similar to the beloved.God loves us, and it is because He loves us that He wants to save us and bring us back to Him. God is moved by love, by His very Nature (the Divine Nature): Love.
So, since Love (the Holy Spirit) makes the One Who loves (Jesus) similar to the loved one (us), He wanted to get as close as possible to us (including all what constitutes us as “humans”, i.e. culture). He then wanted to be like us, as much as He could (except for sin). This means that all the pores of his Human Nature (body, soul and spirit) had to open, develop, and be similar to ours, and “discover” us. Of course in His Human Nature, He is purer than us. But “pure” means as well with greater sensitivity, greater intelligence, greater capacity to love.
“He [humanly] learned obedience” (He 5:8)
He wanted to be similar to us, starting with His Culture: He is born amongst the “chosen People of God”, in a specific moment in history, in a specific land, with a specific language, specific habits, traditions, concepts: in a word: He had a specific Culture.
He certainly, out of love, did observe us humans, and studied us, in order to love us more, and to help us better. Of course He had high knowledge, coming from his Divinity and from the Holy Spirit, reaching his soul. But still, in order to use his “human nature” according to the laws and functioning of his human nature, out of love, He had to “undergo” the speed (the slowness) and capacity of digestion of the human process of growth (it takes years, rightly)!
Sometimes we pay less attention to the 30 years of preparation of Jesus. At 12 he becomes adult according to the Jewish tradition. He goes to the Temple.

Jesus, at 12, in the Temple
Then, after that, he comes back to his home town and to his home town. And continues the human process of growth, from 12 to 30: this means 18 years of “work” of preparation. Then he went down to Nazareth with them and was obedient to them.” (Luke 2:51)
Jesus and Joseph
This great “work” He goes through is very important in order to understand the whole process of Salvation/Redemption.
He saves us with His humanity (as pointed out in a previous post (Spiritual Journey 2), mentioning a Council that defined that issue, “Constantinople III, 680-681”), and His Human Nature (body, soul and spirit) is like a “hand” (or a “sponge”) that is supposed to “grasp” us, hold us, embrace us, surround us, absorb us, be united with us.
His Body holds and embraces for inside our body,
his Soul our soul, and
his spirit our spirit.
(his “spirit” is the highest point of his soul; saint Thomas Aquinas calls it in latin: mens)
In order to “hold” us tightly, and be united with us, His human Nature (the “tool”) has to be ready: mature, adult, knowing his own culture, the words, the mentality, the habits, and tons of things that constitutes a “culture”.
With His Human Nature he had to undergo this journey in order to get closer to us. So these years (from 12 to 30) are very important for that purpose.

During these years He is constantly getting (with his human nature) closer and closer to us, getting a better inside understanding of “who we are”, our weaknesses… He is our Saviour, and he took the human journey of growth to be as well “perfectly human” (as it is needed for that type of salvation: the salvation “out of love”).
In order to save, out of love, according to God’s vision, He needs to be perfect God and perfect human. Coming out of the womb of our Lady doesn’t make him (or any other being) a fully human being. In the animal world, us humans (we are more than animals but it is just a comparison), we are the specie that requires the greatest number of years to achieve maturity, and readiness for life. The process in long. We do not become humans by just coming out of the womb of our mother. We need years and years.
So, in order to become our Perfect Saviour, Jesus had to become Perfectly Human. In order to reach that “perfection”, he had to undergo, out of love, this journey of human, cultural growth.
He wanted for us Mercy, He wanted to understand us, from inside of his Human Nature, therefore, He went through this journey. This is why, I said that at that time (at the age of 30), when he started His Public Mission, he was ready, in his Human Nature.
Of course, at each age, He was perfect: He had the human perfection of each age. But He still had to go through all the ages. If He really wants to save us “out of Love” he had to be as close as possible to us, and similar to us as much as possible. So we can recognise in Him not only “the God that knows everything”, but “the Human Nature” that feels us, that carries us, that underwent through all that trouble to Save us.
The preparation of His Words
Plus, you have to add the fact that His words, all the words that He will use to save us, were like prepared, backed, in his Human Nature, during all these years. They came out of His Human Nature (brain, soul,..), full of Divine life, truthful to God, but as well truly truthful to us humans (having a human aspect to them).
Jesus had to “form” them in Him.
It is too easy to consider that everything landed in his humanity, in his human nature, from above, by the action of the Holy Spirit. But this understanding is heretical, in the sense that it doesn’t respect a theological rule that says that each nature had to work and act according to its own rules and functions (see st. John Damascene, “De fide orthodoxa”, taken on board by st. Thomas Aquinas “Summa Teologica” IIIa Pars).
The words He uttered, these words that are described as “Spirit and Life” (see John 6), i.e. that contain “Holy Spirit” and “Divine Life” have been formed in His Human nature throughout the years: his sensibility, his choice, his brain, his culture, what he saw and received in his culture from his mom, his adoptive father, his family, his human experience, what he noticed and observed.
These words that He uttered and that saint John, in his Gospel, admires, are really a great achievement. They are like Him, in the same fully Divine and fully human. They took time to “bake” in Him, adhering to His human rhythm of growth, forming them, in Him, by the help of the Holy Spirit and his prayer. (Here I am speaking about the human side of Jesus).
His Perfection, at each stage of His human life, is not at all undermined by that growth. He is God at all the stages of His life. He has as well the human perfection of each stage of His life. But still, he grew in wisdom and stature, and in favour with God and men” (Luke 2:52).