Very true.
Therefore if one is, the one is all things, and also nothing, both in relation to itself and to other things.
Certainly.
2.a. Well, and ought we not to consider next what will be the consequence if the one is not?
Yes; we ought.
What is the meaning of the hypothesis—If the one is not; is there any difference between this and the hypothesis—If the not one is not?
There is a difference, certainly.
Is there a difference only, or rather are not the two expressions—if the one is not, and if the not one is not, entirely opposed?
They are entirely opposed.
And suppose a person to say:—If greatness is not, if smallness is not, or anything of that sort, does he not mean, whenever he uses such an expression, that 'what is not' is other than other things?