In plain words
But the man of today, instead of being grateful, is becoming ungrateful. Gratitude is the chief life-breath in man. Among the hundred and eight names of God there are special names. 'Om himaghnāya namaḥ, kṛtaghnaghnāya namaḥ, Om tamaghnāya namaḥ.' So they call on Him. Tamaghna means the one who drives away darkness. What is it that drives away darkness? Light alone. So, where this light is, there is no room for darkness to stay. God roots out this Ajñāna precisely because He is everywhere. Himaghnāya namaḥ. The snow that lies so thick, mañcugaḍḍanaṃ, slowly melts away as the sun shines. So, through the rising of the sun, even snow that lies hard as a block turns into flowing water. If there is no light at all, darkness does not go. If darkness is to go, there must be light. If there are no rays of the sun at all, the snow does not melt. If the snow is to melt, the sun must rise.
In just the same way, without gratitude we will not have even our divine vision. Divine vision is like the sunrise. The rays of the sun lie hidden within every eye. In the Puruṣa Sūkta: candramā manasō jātaḥ cakṣōḥ sūryō ajāyata. Our eyes are the very power of light that is in the rays of the sun. Its meaning is that the sun will put out the sight of the ungrateful man. That is, he makes him blind, it is said. When he draws his rays back to himself, what else can that man become but blind? In the world there is atonement for any sin, but for the ungrateful man there is no atonement at all. So, moṇṭumodaṭa, man's chief aim is gratitude: never to forget the good that was done to him. When we wish to reach the right state in the future, we must recognise our present. We must see that we never forget the good done to us today. What we do hereafter lies in our present. So we must look upon gratitude as the right mark to bear. Gratitude is itself the chief quality in man. We must foster qualities like these and foster a broad heart that gives society the gratitude it deserves. One meaning is that those who seek to go forward must not forget what went before. If we forget the very people who helped us in our troubles and our sorrows today, there will be no happiness or peace at all in the future.