First of all, he defined the content and the method of the intellectual process by which man attains to “acquired intellect.” If we say that the intellect becomes actual and eternal by comprehending the Ideas and becoming one with them,[101] it follows that the content of the Ideas themselves must be actual and eternal. For how could something real and eternal be created by the acquisition of something itself unreal or not eternal? Thus we exclude from the category of Ideas by the apprehension of which the acquired intellect is obtained: (1) those sciences which contain only abstract laws and not the explanation of real things, such as mathematics and logic; (2) those sciences which teach not what actually exists, but what ought to be done for the achievement of certain objects, such as ethics and æsthetics; (3) the knowledge of individual forms, which have only a temporary existence in combination with matter, such as the histories of famous men and the like. All knowledge of this kind, though it is useful and in some cases even necessary as preparation, is not in itself capable of making the intellect actual. What, then, are the Ideas by the apprehension of which the intellect does become actual? They are those whose content is true and eternal Being. This Being includes (going from lower to higher): (1) the generic forms of all things in the lower world, which are, as we know, constant; (2) the heavenly bodies, which, though compounded of matter and form, are eternal; (3) the forms which are free of matter (God and the separate Intelligences).[102] All this relates to the _content_ of the intellectual process; but there is also a very important definition of its _method_—a definition which is implied in the conception itself. The result must be achieved _by the intellect’s own activity_: that is to say, man must apprehend the truth of Being by rational proofs, and must not simply accept truth from others by an act of faith. For apprehension by this latter method is purely external; reason has had no active part in it, and therefore that union of the intellect with its object, which is what makes the intellect actual, is lacking.[103] And now let us see what are the ethical consequences of this idea.