The QM class I originally took used Liboff. I could barely understand a word of it and ended up dropping the class. Later I found the Shankar book and was thrilled with it by comparison. I&#x27;m not a math whiz though, so lack of &quot;rigor&quot; on a first pass is just fine by me. For an intro level text for the average person, I found Shankar was one of the few accessible ones.<p>Haven&#x27;t read Griffiths yet so I can&#x27;t comment on it.