It is the business of the future to be dangerous; and it is among the merits of science that it equips the future for its duties. — Alfred Whitehead
Once upon a time, long ago in a world far away, Lisp had many features which other languages did not have. Automatic storage management, dynamic typing, an interactive environment, lists, symbols … and macros, which allow you to seamlessly extend the language you have into the language you want and need.
But that was long long ago in a world far away where giants roamed the earth, trolls lurked under every bridge and, they say, gods yet lived on certain distant mountains.
Today, and in this world, many many languages have automatic storage management, are dynamically typed, have symbols, lists, interactive environments, and so and so and so. More of these languages arise from the thick, evil-smelling sludge that coats every surface each day: hundreds, if not thousands of them, like flies breeding on bad meat which must be swatted before they lay their eggs on your eyes.
Lisp, today and in this world not another, has exactly one feature which still distinguishes it from the endless buzz of these insect languages. That feature is seamless language extension by macros.
So yes, macros are dangerous, and they are hard and they are frightening. They are dangerous and hard and frightening because all powerful magic is dangerous and hard and frightening. They are dangerous because they are a thing which has escaped here from the future and it is the business of the future to be dangerous.
If macros are too dangerous, too hard and too frightening for you, do not use Lisp because macros are what Lisp is about.
This originated as a comment by my friend Zyni: it is used with her permission.