Why must Mary be "Immaculate"?

[ConstantineTG]

Seems to me that the teaching of the Incarnation would indicate that Christ takes on fallen human nature. Now what does it then mean to “perfect” it.

He’s clearly in a body that can die…unless you want to posit that he “perfects” his flesh at the moment of his conception so that it cannot die…and THEN…de-perfects it while on the Cross so it can die…?

How do you explain that he ages…

Or that he grows in knowledge and wisdom?

Can we say its a process? That the perfection is complete after the resurrection, that is why all of us must die first and be resurrected as Christ died and resurrected.

Now I’m getting more confused. I want this explained in an Eastern way. Since we do not believe there is a stain of Original Sin, so Mary was conceived the same way we are. But at the moment of her conception she has been filled by God with overflowing grace. So Christ inherits a humanity the same as ours since the grace within Mary didn’t change her human nature. Correct?