but , whether true or false , my opinion is that in the world of knowledge the idea of good appears last of all , and is seen only with an effort ; and , when seen , is also inferred to be universal author of all things beautiful and right , parent of light and of the lord of light in this visible world , and the immediate source of reason and truth in the intellectual ; and that this is the power upon which he who would act rationally either in public or private life must have his eye fixed .