Aristotle (Metaph. XII. 9) now solves many other doubtful questions, for instance, whether thought is compound, and whether science is the object of science itself. “Some further doubts arise as to thought (νοῦς), which seems to be of all things the most divine; but it is only with difficulty that we can conceive under what conditions (πῶς δ̓ ἔχων) it is a thing of this sort. When it thinks of nothing, but is in a state like that of a sleeper, what constitutes its superiority? And when it thinks, but something else is dominant all the time (ἄλλο κύριον), that which is its substance is not thought (νόησις), but a potentiality;” it would not be in eternal activity. “In this way it would not be the highest substance; for it is” (active) “thought (τὸ νοεῖν) that gives it its high rank. If now, further, thought or thinking is its substance, what does it think? Itself or another? And if another, is it always the same, or something different? Does it also not make a difference, whether it thinks of what is beautiful or what is casual? In the first place, if thought is not thinking, but only the power to think, continuous thinking would be laborious for it,” for every power wears itself out. “In the next place, something else would be more excellent than thought, namely that which is thought (νοούμενον); and thinking and thought (τὸ νοεῖν καὶ ἡ νόησις) will be present to the mind in understanding what is most inferior. As this is to be avoided (in the same way that it is better not to see some things than to see them), thinking would not constitute the best. Thought is therefore this, to think itself, because it is the most excellent; and it is the thinking, which is the thinking of thinking. For understanding and sensation and opinion and deliberation seem always to have an object other than themselves, and to be their own objects only in a secondary sense. Further, if thinking and being thought of are different, in relation to which of the two is the Good inherent in thought? For the Notion[92] of thinking and that of the object of thought are not the same. Or, in the case of some things, does the science itself constitute that which is the object of science? In what is practical the thing is the immaterial substance and the determination of the end (ἡ οὐσία καὶ τὸ τί ἦν εἶναι), and in what is theoretical it is the reason and the thinking. As therefore thought and the object of thought are not different, these opposites, so far as they involve no connection with matter, are the same thing, and there is only a thought of the thing thought of.” Reason which thinks itself, is the absolute end or the Good, for it only exists for its own sake. “There still remains a doubt whether that which thinks is of composite nature or not; for it might undergo change in the parts of the whole. But the Good is not in this or that part, for it is the best in the universe, as distinguished from it. In this way the Thought which is its own object subsists to all eternity.”