People in heaven are continually progressing toward the springtime of life. The more thousands of years they live, the more pleasant and happy is their springtime. This continues forever, increasing according to the growth and level of their love, thoughtfulness, and faith.
As the years pass, elderly women who have died of old age—women who have lived in faith in the Lord, thoughtfulness toward their neighbor, and in contented marriage love with their husbands—come more and more into the flower of growing youth and into a beauty that surpasses any notion of beauty accessible to our sight. Their goodness and thoughtfulness is what gives them their form and gives them its own likeness, making the pleasure and beauty of thoughtfulness radiate from every least corner of their faces so that they become actual forms of thoughtfulness. Some people have seen them and have been stunned. The form of thoughtfulness that is open to view in heaven is like this because it is thoughtfulness itself that both gives and is given visible form.
In fact, it does this in such a way that the whole angel, especially her face, is virtually thoughtfulness itself appearing to open perception. When people look at this form, its beauty is unutterable, affecting the very inmost life of the mind with thoughtfulness. In a word, to grow old in heaven is to grow young. People who have lived in love for the Lord and in thoughtfulness toward their neighbor are forms like this, or beauties like this, in the other life. All angels are forms like this, in infinite variety. This is what makes heaven.
from Heaven and Hell, Section 414