Have you ever worked with somebody who just rubbed you the wrong way? You'd never say anything about it in person, but everything they do just ticks you off. Maybe it's their sense of humor, or the way they blow their nose, or their habit of evangelizing fad diets to any and all in earshot. You're not alone.
In the early 20th century, Dr. Santiago Ramón y Cajal (AKA "the father of neuroscience") was losing it over this obnoxious guy Sigmund — as in, Sigmund Freud. Although the fathers of their respective fields enjoyed a reasonably cordial working relationship, Cajal was so riled up by Freud's theories that he secretly devoted the last 16 years of his life to disproving them.