Thinking has become a disease. Disease happens when things get out of balance. For example, there is nothing wrong with cells dividing and multiplying in the body, but when this process continues in disregard of the total organism, cells proliferate and we have disease. The mind is a superb instrument if used rightly. Used wrongly, however, it becomes very destructive. To put it more accurately, it is not so much that you use your mind wrongly—you usually don't use it at all. It uses you. This is the disease. You believe that you are your mind. This is the delusion. The instrument has taken you over.
— Eckhart Tolle