Chazal - Everything They Say Is True

 Igros Moshe (Y.D. 2:70): It is not possible that the generations following the completion of the gemora would know about that which is not visible to the naked eye. Only the Sages of the Talmud (Chazal), with their kabbala and their sevara, could possibly know about it. We are obligated to believe that everything that they say is true. In contrast, after the completion of the Talmud even the Gaonim...