Many years ago, one of my ex-professors had this unique habit. Everytime I said something stupid, he used to raise his eyebrows and stare at me till I stumbled towards the right answer on my own. As my work progressed, the frequency of such incidents reduced gradually to zero. I was elated, thinking that I am improving. During my final meeting with him, I observed him closely. My illusion was shattered and I understood the real reason. One year of working with me and his eyebrows had permanently shifted to a higher position on his forehead