Mixing Yoga and 19th-Century Jewish Pietism

In a recent book, Edith Brotman seeks to combine yoga with musar, a Jewish pietistic movement founded in 19th-century Russia that focused on rigorous introspection and the ethical perfection of the individual. Pairing spiritual improvement through exercise as promised by yoga with spiritual improvement through strict self-discipline as promised by musar sounds appealing as far as it goes, writes Abe Socher, but how far does it go? Among much else, it misses something of the original message of Israel Salanter, founder of the musar movement: