What can "explain one of the most distressing features of the neo-Kantians: the fierceness and bitterness of their polemics, the nastiness of their ad hominem arguments, which destroyed personal friendships and decent collegial relations? Heinrich Rickert (Heidelberg) wrote to Paul Natorp (Marburg): 'Just because we critical idealists agree on fundamentals, we have to take the knives to each other." Klaus Kohnke From Klaus Christian Köhnke's _The Rise of Neo-Kantianism_ (Cambridge University Press 1991), p. x: