“This perishable body, O son of Kunti, is known as Kshetra; those who are acquainted with the true nature of things call the soul who knows it, the Kshetrajna. Know also that I am the Knower in every mortal body, O son of Bharata; that knowledge which through the soul is a realization of both the known and the knower is alone esteemed by me as wisdom. What the Kshetra or body is, what it resembleth, what it produceth, and what is its origin, and also who he is who, dwelling within, knoweth it, as well as what is his power, learn all in brief from me. It has been manifoldly sung by the Rishis with discrimination and with arguments in the various Vedic hymns which treat of Brahman.
“This body, then, is made up of the great elements, Ahankara — egotism, Buddhi — intellect or judgment, the unmanifest, invisible spirit; the ten centers of action, the mind, and the five objects of sense; desire, aversion, pleasure and pain, persistency of life, and firmness, the power of cohesion. Thus I have made known unto thee what the Kshetra or body is with its component parts.
“True wisdom of a spiritual kind is freedom from self-esteem, hypocrisy, and injury to others; it is patience, sincerity, respect for spiritual instructors, purity, firmness, self-restraint, dispassion for objects of sense, freedom from pride, and a meditation upon birth, death, decay, sickness, and error; it is an exemption from self-identifying attachment for children, wife, and household, and a constant unwavering steadiness of heart upon the arrival of every event whether favorable or unfavorable; it is a never-ceasing love for me alone, the self being effaced, and worship paid in a solitary spot, and a want of pleasure in congregations of men; it is a resolute continuance in the study of Adhyatma, the Superior spirit, and a meditation upon the end of the acquirement of a knowledge of truth; — this is called wisdom or spiritual knowledge; its opposite is ignorance.”s
— The Bhagavad-Gita Chapter 13