Answer:
What Washington called "the spirit of party" was, he claimed, "inseparable from our culture, having its origin in the greatest impulses of the human mind "— namely, the tribal desire to divide the world into" we "vs." they, "into competitor and opposing classes. This spirit can then easily become a desire to see winning "our side," irrespective of whether our side is better than "their side," irrespective of the issues involved or the facts of the matter.