One thing seems clear: Our Lord is emphasizing, through this promise, the infinite value of Confession and Communion as miracles of mercy. He wants us to realise that since the Eucharist is His own Body, Blood, Soul and Divinity, it is the ''Fountain of Life". The Eucharist is Jesus, Himself, the Living God, longing to pour Himself as Mercy into our hearts.

Why would Our Lord feel the need to emphasize this? Because so many people do not really understand it. They either see no need to receive Holy Communion, or they receive it simply out of habit. As St. Paul expiains in his letter to the Corinthians, they eat the bread or drink the cup of the Lord unworthily, "without recognizing the body of the Lord" ( 1 Cor 11:27-29 ).
To be continued,

In His revelations to Blessed Faustina Our Lord makes it very clear what He is offering us in Holy Communion and how much it hurts Him when we treat His presence with indifference:
My great delight is to unite Myself with souls, When I come to a human heart in Holy Communion, My hands are full of all kinds of graces which I want to give to the soul. But souls do not even pay attention to Me, they leave Me to Myself and busy themselves with other things. Oh, how sad I am that souls do not recognise Love! They treat Me as a dead object

It pains Me very much when religious souls receive the Sacrament of love merely out of habit, as if they did not distinguish this food. I find neither faith nor love in their hearts. I go to such souls with great reluctance. It would be better if they did not receive Me.
To be continued