We each have two sides: intellect and will. The will is the first part; the intellect comes second. The kind of life we have after death depends on our volitional side, not our intellectual side. From infancy through adolescence the Lord forms our will by instilling innocence in us and goodwill toward our parents, caretakers, and playmates, and by other means that we are unaware of. These are heavenly attributes. If these heavenly attributes were not first instilled in us as babies, children, and youths, we could never become human. That is how the first level is formed.
We are not human, however, unless also equipped with an intellect. The will alone does not make us human, but intellect together with will. Moreover, we cannot develop an intellect without both secular and religious knowledge. As a result, we need to absorb this knowledge by degrees, beginning in childhood. That is how the second level is formed.
When the intellectual side has received an education in both kinds of knowledge, especially the knowledge of truth and goodness, then we can first be reborn. And when we are being reborn, the Lord uses that knowledge to graft true ideas and good impulses onto the heavenly gifts we have received from him since infancy. In this way our intellectual abilities fuse with our heavenly gifts. When the Lord has united the two in this way, we receive the gift of love for others—a product of conscience—and start to act on it. This is how we first receive new life, which comes gradually. The light we enjoy in this new life is called wisdom, which now plays the leading role and overshadows any mere ability to understand. That is how the third level is formed.
If we become this kind of person during bodily life, in the next life we are constantly being perfected.
This indicates what the light of understanding is and what the light of wisdom is.
from Secrets of Heaven, Volume 2, Section 1555