"A trait that is found among Jews, which is actually essential to their existence, is a high degree of stubbornness.
From this we may understand that every Jew who did not have the ability to cling—stubbornly, steadfastly, ceaselessly—to his identity, his faith, the structural pattern of his life, would not have had the ability to continue to exist, or at least to continue existing as a Jew.
This stubbornness is part of the structural makeup, the essential nature, of the Jew.
In principle, it is this obduracy—'for it is a stiff-necked people' (Exodus, 32:9, 34:9; Deuteronomy 9:13, 10:16)—that is the basis for the hold on the very essence of being a Jew, of remaining a Jew, and, in another sense, of remaining alive at all.
However, like all other character traits, it does not confine itself only to the sphere of beliefs and opinions, but pervades all other aspects of the mind and of life.
So a person whose stubbornness and persistence are no longer directed at maintaining Judaism still retains these qualities but directs them to other aims—either to business and material success, or to intellectual enterprises and so on."