“We have but one method of acquiring knowledge. From the lowest man to the highest Yogi, all have to use the same method; and that method is what is called concentration. The chemist who works in his laboratory concentrates all the powers of his mind, brings them into one focus, and throws them on the elements; and the elements stand analysed, and thus his knowledge comes. The astronomer has also concentrated the powers of his mind and brought them into one focus; and he throws them on to objects through his telescope; and stars and systems roll forward and give up their secrets to him. So it is in every case -- with the professor in his chair, the student with his book -- with every man who is working to know.”
(CW: Vol.2: Practical Vedanta and other Lectures: The Ideal of a Universal Religion (p. 390-391)).