Eggs that have not been damaged or cracked should be put back in the nest, because if they get too cold, the developing baby bird will die.
Sometimes hens will through out the eggs that are not good, or you will find them on the side of the nest. They know when something is wrong with the egg and it's not going to hatch.
I heard that birds can recognize the smell if some one touches it's egg and they does not accept some one touching them.
It's an old wives tale about not touching the eggs (look it up on the net), if it doesn't appear to be damaged, put it back. If the bird intentionally knocked it out of the nest because there may be something wrong with it, they will knock it out again.
In that case, there's no point putting it back in.
If you do the mother will not care for the egg possibly eat it.
It depends on what kind of bird. My grandpa raised many different kinds, and if it is like a love bird, canary, dove, no, not only will the mom not care for it but at this point it wouldn't matter what you did because those kinds of birds rarely even take care of their babies if they fall out of the nest. If it is a birds that has their nest on the ground, like quail, simply take a clean soft rag and put it back.
If it is a parakeet, or budgie, you might have a chance because they are already probably very used to your scent on their cage, so in that instance I would put it back if it were me....maybe call a vet?
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.