The Sefirah associated with Lag B'Omer is Glory witin Glory (Hod shebe Hod), or gratitude inside gratitude. When a man is grateful to God, he should add that he is grateful for the possiblity of standing in front of God and being grateful. He thus completes and perfects his gratitude with gratitude.
However, he does not have to stop there. He can now be grateful for his capacity of being able to be grateful for being grateful. This chain has no end. It is reminiscent of God's desire to create the world, which had to be preceded with a desire to have a desire, and so on, also ad infinitum.
Compare this to Littlewood's idea of gratitude with potential infinity.
“The following idea, or coda to the series, was invented too late (I do not remember by whom), but what should have happened is as follows. I wrote a paper for the Comptes Rendus which Prof. M. Riesz translated into French for me. At the end there were 3 footnotes. The first read (in French) 'I am greatly indebted to Prof. Riesz for translating the present paper.' The second read 'I am indebted to Prof. Riesz for translating the preceeding footnote.' The third read 'I am indebted to Prof. Riesz for translating the preceeding footnote,' with a suggestion of reflexiveness. Actually I stop legitimately at number 3: however little French I know I am capable of copying a French sentence.” (Littlewood, Mathematical Miscellany).
Why does Littlewood stop at 3 while we continue ad infinitum? Obviously, because he is grateful not for the quality of being great, but for translating his gratitude. It is because our gratefulness is for gratefulness itself that we get into the infinite loop – which is better at stretching the mind than the finite.
Art: Gustave Courbet - Eternity