Gratitude is one of the twelve attributes of the Mother’s symbol.
O Supreme Reality, O Supramental Truth, this body is totally vibrant with an intense gratitude. Thou hast given to it, one after another, all the experiences that can lead it most certainly towards Thee. It has come to the point where identification with Thee is not merely the one thing desirable, but the only thing possible and natural.
The Mother – Words of the Mother – III: CWM, Vol. 15, p. 282
Gratitude: It is you who open all the closed doors and let the Grace which saves penetrate deeply.
Gratitude: A loving recognition of the Grace received from the Divine. A humble recognition of all that the Divine has done and is doing for you. The spontaneous feeling of obligation to the Divine, which makes you do your best to become less unworthy of what the Divine is doing for you.
Detailed gratitude: the gratitude that awakens in us all the details of the Divine Grace.
Integral gratitude: the whole being offers itself to the Lord in absolute trust.
Mental gratitude: the gratefulness of the mind for what makes it progress.
The Mother – Words of the Mother – II: CWM, Vol. 14, p. 154
Ultimately, gratitude is only a very slightly colored hue of the essential Vibration of Love.
The Mother – Agenda: Vol. 4, p. 427