But we have now posited that it is impossible for anything at the same time to be and not to be, and by this means have shown that this is the most indisputable of all principles.-Some indeed demand that even this shall be demonstrated, but this they do through want of education, for not to know of what things one should demand demonstration, and of what one should not, argues want of education.
Guk, ordea, arestian onartu dugu ezinezkoa dela aldi berean izatea eta ez izatea, eta hori 5) dela eta, printzipio guztietan sendoena huraxe dela frogatu dugu.