Rabbi Kaplan, Z"L, makes a great insight on this short, but extremely deep book. He uses his knowledge in physics to make us approach to such a very ancient text in today's language. Basically a meditative text, Kaplan suggests its basic applications as well as an insight on how to make a Golem. Anyway, as he states elsewhere in this, and his other titles, all these practices should be treated with maturity and some respect (if you don't believe in this stuff's truth, just skip that), for you can get psychologically or spiritually damaged. Absolutely recommendable.