They say we all lose 21 grams at the exact moment of our death... Everyone. 

Twenty-one grams. 

The weight of a stack of five coins. 

The weight of a hummingbird. 

The weight of a chocolate bar. 

The weight of our sensations and thoughts, desires and beliefs.

The reason of our judgement to Hell and Heaven.

The immaterial aspect or essence of a human being, which confers individuality and humanity.

It's the weight of the HUMAN SOUL.