A wise man said: before you speak， let your words pass through three gates. At the first gate， ask yourself， "Is it true？" At the second gate， ask "Is it necessary？" At the third gate， ask， "Is it kind？"
The fundamental point in fabricating a chain reacting machine is of course to see to it that each fission produces a certain number of neutrons and some of these neutrons will again produce fission.
