Why should we assume that all knowledge can be put into words? Mystics have often asserted that the truths of mystical experiences are impossible to put into words, and yet are the deepest truths of all. ‘A truth cannot lose anything by being written down’, Hegel said; but perhaps this simple claim was the first step down the path away from truth. Should we not have stopped Hegel right there, and insisted on the validity of knowledge too pure for words?