Always the same

The text below is from a book, Man's search for meaning.

Can you tell me What the meaning of the underlined part is?

[To me, it doesn't make any sense, because it seems OK to be taken out.
But I think IT'S JUST MY WILD GUESSING.
I don't think this author, Viktor Frankl, who was one of Nazi concentration camp survivors and had overcome his trauma and built a theory that succeeded and advanced Freudian psychotherapy, put down any sentence that can be removed without any change of meaning.]

If my wild guessing is not right, what is the meaning and role of this phrase, "always the same?"

Larks rose to the sky and I could hear their joyous song. There was no one to be seen for miles around; there was nothing but the wide earth and sky and the larks' jubilation and the freedom
of space. I stopped, looked around, and up to the sky—and then I went down on my knees. At that moment there was very little I knew of myself or of the world—I had but one sentence in mind—always the same: "I called to the Lord from my narrow prison and He answered me in the freedom of space."