"[Buddhism is] a Hindu phenomenon, a natural product, so to speak, of the age and social circle that witnessed its birth. When we attempt to reconstruct its primitive doctrine and early history, we come upon something so akin to what we meet in the most ancient Upanishads and in the legends of Brahmanism, that it is not always easy to determine what features belong peculiarly to it."
January 1, 1970
https://en.wikiquote.org/wiki/Auguste_Barth