Apples of Iðunn are the ambrosia of life, ódáinsfæða (literally: the “non-death nourishment”), amrit (non-death), the nurturing flow of wisdom to keep us ever young – however old this our present body becomes.

The gods love those who are ever-young (biologically speaking) however old this present body becomes. This is how the old Greek saying should be understood.
Sometimes we are Loki-stupid (Loki is mankind), as not to appreciate our immortality. Let that not ever ever happen again.
The only “place” the apples of Iðunn are on stock is in pure consciousness. We shall nýsa niður, be nistha, to acquire them, the apples of immortality.
Iðunn as a nut indicates what is kept in timelessness: the potential of blossoming.

See also Bragi and Iðunn
Loki
Theory by Guðrún: Loki is mankind.
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Listen to pronunciation: Iðunn, epli Iðunnar; Bragi