Harold B. Lee – "The Place of the Living Prophet, Seer, and Revelator"
Address to Seminary and Institute of Religion Faculty, July 8, 1964
It is not to be thought that every word spoken by the General Authorities is inspired, or that they are moved upon by the Holy Ghost in everything they speak and write. Now you keep that in mind. I don’t care what his position is, if he writes something or speaks something that goes beyond anything that you can find in the standard works, unless that one be the prophet, seer, and revelator–please note that one exception–you may immediately say, "Well, that is his own idea!" And if he says something that contradicts what is found in the standard works (I think that is why we call them "standard"–it is the standard measure of all that men teach), you may know by that same token that it is false; regardless of the position of the man who says it.
via LDSLastDays.com