Bill: I put the discussion about life in a footnote because this is introductory material. The first thing a novice needs to know here is that you can make groups with two firm eyes that do not need to be defended. After that they need to know about groups that, when attacked, can make two firm eyes.
Grauniad: The fact that each eye in the diagram has only one point may be misleading to novices. I think this critical concept would be better demonstrated by discussion of a more general diagram in which at least one eye has more than one point. Something like this?
Bill: Why not both examples? :-)
Grauniad: What does the first add to the second? :-)
Bill: The first one is the prototype. The second one generalizes the first.
Robert Pauli: Honestly, Bill, this footnote style doesn't attract me much (and lost the seki case, BTW). Shouldn't it better (and without footnote) be something like
Crystal clear and to the point, not?
Bill: Charles Matthews prefers the term, safe, to indicate stones that are alive without defense. Not everybody uses it that way, but, since there is a reasonable (and traditional) alternative, alive, for stones that may require defense, I am happy to stick with the traditional term, and not equate the two.
Logically, your sentence is clear. Operationally, it gets into areas that are beyond the ken of novices. How do you reach seki or form two eyes? And it is not really to the point of this page, but of the alive page.