Manitou studies the expression Am Kshe Oref (stiff-necked people) from the Golden Calf episode. Rashi explains it as turning their necks away from those who admonish them, refusing to listen. The real difficulty is why repentance seems impossible here. Manitou reveals that this trait originates with the Erev Rav (mixed multitude), but Israel took it upon itself out of solidarity for the salvation of humanity.