Beauty has many aspects. Gratefulness is one such aspect of beauty. When you dont feel a sense of lack, then you feel grateful. You cannot be grateful and feel lack. The two cannot co-exist.
When you feel lack, grumbling begins from some corner. If you are grumbling, the negativity will increase. For those who do not have this knowledge, there is no way out of their grumblings, because once they start grumbling, they keep grumbling throughout their life. They feel some lack today and tomorrow they feel something else is lacking. There is no end to it. It is then that demand arises and when demand arises, your mind doesnt think clearly, doesnt focus clearly, doesnt function properly; and naturally you tend to lose everything.
That is why Jesus said, Those who have will be given more; as for those who do not have; even what they have will be taken from them.” If you are grateful, more things will flow to you. And when you complain and grumble, even what little joy, peace or love they have come into this world with, will be lost. This is the law of nature.
This explains why grandmothers in India have a habit of saying, Everything is full.