The difference between true knowledge and book knowledge is the same as that between gold and banknotes
"The difference between true knowledge and book knowledge is the same as that between gold and banknotes. The notes are not always worth much; they may even lose all their value following political or social unrest, whereas gold never loses its value, whatever the circumstances. This is why anyone who has gold will never be destitute.
Book knowledge, like banknotes, may in certain circumstances no longer be of use to you. If, on the other hand, your knowledge comes from wisdom – the wisdom that is based on personal, living experience – then you are in possession of gold. In all circumstances and all conditions, this knowledge remains valuable; it lights up your path, it offers you solutions and brings you peace."