Toward the beginning of Challenging Nature, Lee Silver sounds a defensive note: "I do not claim that all expressions of spirituality are harmful or bad. Nor do I think that all biotech applications are inherently good, ethical, or risk-free." It was wise of the Princeton molecular biologist to include those two sentences. The reader might otherwise have been misled by every other sentence in the book into thinking that Silver considers religion a regrettable—though regrettably ineradicable—feature of human society, and that no serious limits should be placed on biotechnology.