Swami Vivekananda

 ‘Religion deals with the truths of the metaphysical world just as chemistry and the other natural sciences deal with the truth of the physical world. The book one must read to learn chemistry is the book of (external) nature. The book from which to learn religion is your own mind and heart. The sage is often ignorant of physical science because he reads the wrong book—the book within; and the scientist is too often ignorant of religion, because he, too, reads the wrong book—the book without.’