“It has been pointed out, for example, that the invention of eyeglasses in the twelfth century not only made it possible to improve defective vision but suggested the idea that human beings need not accept as final either the endowments of nature or the ravages of time. Eyeglasses refuted the belief that anatomy is destiny by putting forward the idea that our bodies as well as our minds are improvable. I do not think it goes too far to say that there is a link between the invention of eyeglasses in the twelfth century and gene-splitting research in the twentieth.”