Nobody was ever replaced in life, no hole completely filled or loss totally healed. You didn't need a medical degree to know that the human body really wasn't stronger in the broken places. Like any bone, the cracks would always show if you looked hard enough.
Sometime in your life, hope that you might see one starved man, the look on his face when the bread finally arrives. Hope that you might have bought it or baked it or even kneaded it yourself. For that look on his face, for your meeting his eyes across a piece of bread, you might be willing to lose a lot, or suffer a lot, or die a little, even.
Do not be too timid and squeamish about your actions. All life is an experiment. The more experiments you make the better. What if they are a little coarse, and you may get your coat soiled or torn? What if you do fail, and get fairly rolled in the dirt once or twice? Up again, you shall never be so afraid of a tumble.