Chazon Ish (Letters 1:15):.. It is at the roots of our faith that all that is said in the gemora whether it is in the Mishna or gemora whether it is halacha or agada - all these things were revealed to us through the medium of prophetic power ... There is in fact a major distinction between the power of prophecy and ruach hakodesh. Prophecy transcends the human intellect entirely. Therefore, someone who has reached the level of prophecy is able to acquire wisdom directly without any intellectual effort or involvement. In contrast, ruach hakodesh requires tremendous thought and analysis until he is given additional supernatural understanding. Without this effort, this special understanding is never achieved. One of the fully accepted foundations of faith is that ruach hakodesh is critical to properly understanding the truth in the Torah that was given through prophecy. That is because Torah is not just probably true but is absolutely true. Consequently we are greatly distressed to hear any aspersions cast on the words of Chazal whether it is Halacha or agada. It is equivalent to hearing blasphemy. A person who deviates in this way is according to our tradition as one who denies the words of Chazal and his shechita is invalid and he is unfit to serve as a legal witness and other issues.