That's not quite a good principle, if left unqualified. A queen can threaten just about anything and, except for a knight, other pieces can threaten the queen but be taken by it possibly, in FIDE chess, for example.
From Fergus' article on designing good CVs:
'Include pieces with differing powers of movement. Each can attack the other without being attacked back.'
I think what he might have wrote instead of 'Each' was 'Some' or 'Many'.
That's not quite a good principle, if left unqualified. A queen can threaten just about anything and, except for a knight, other pieces can threaten the queen but be taken by it possibly, in FIDE chess, for example.
From Fergus' article on designing good CVs:
'Include pieces with differing powers of movement. Each can attack the other without being attacked back.'
I think what he might have wrote instead of 'Each' was 'Some' or 'Many'.
https://www.chessvariants.com/opinions.dir/fergus/design.html