Mr. Iyengar popularized yoga practice in the west with his 1966 international bestselling book, Light on Yoga. A groundbreaking teacher and practitioner of yoga worldwide, B.K.S. Iyengar wrote thirteen additional books, including, in 2005, a look at the spiritual side of yoga practice, Light on Life

I am branded as Hatha yogi. ‘Ha’ means sun; ‘tha’ means moon. ‘Ha’ means self; ‘tha’ means consciousness. ‘Ha’ means inhalation; ‘tha’ means exhalation. But only many of you think as a solar nerve and a lunar nerve bringing the solar and lunar together on a physiological level is considered as yoga and it is branded as physiological or physical yoga.
— B.K.S. Iyengar, lecture at Harvard University, Yoga '87 DVD

B.K.S. Iyengar photographed at Yoga ‘87, Harvard University, 1987 by Peter Schweitzer

You have heard that I am an extraordinary man . . . I am just an ordinary person like you all, because ‘extraordinary man’ means something beyond the capacity of a human being. I am not.
— B.K.S. Iyengar, lecture at Harvard University, Yoga '87 DVD