The survey of Natural Theism we have completed in the previous chapter will enable us still further to indicate the exact points against which their attacks are directed, and also to estimate the character and force of the weapons employed. With or without design, they are, each in their way, assailing one or other of the principles upon which we rest our demonstration of the being of God. As we proceed, we shall find that Mill and the Constructive Idealists are really engaged in undermining "the _principle of substance_;" their doctrine is a virtual denial of all objective realities answering to our subjective ideas of matter, mind, and God. The assaults of Comte and the Materialists of his school are mainly directed against "_the principle of causality_" and "_the principle of intentionality_;" they would deny to man all knowledge of causes, efficient and final. The attacks of Hamilton and his school are directed against "the _principle of the unconditioned_," his philosophy of the conditioned is a plausible attempt to deprive man of all power to think the Infinite and Perfect, to conceive the Unconditioned and Ultimate Cause; whilst the Dogmatic Theologians are borrowing, and recklessly brandishing, the weapons of all these antagonists, and, in addition to all this, are endeavoring to show the insufficiency of "_the principle of unity_" and the weakness and invalidity of "the _moral principles_," which are regarded by us as relating man to a Moral Personality, and as indicating to him the existence of a righteous God, the ruler of the world. It is necessary, therefore, that we should concentrate our attention yet more specifically on these separate lines of attack, and attempt a minuter examination of the positions assumed by each, and of the arguments by which they are seeking, directly or indirectly, to invalidate the fundamental principles of Natural Theism. (i.) _We commence with the Idealistic School_, of which John Stuart Mill must be regarded as the ablest living representative. The doctrine of this school is that all our knowledge is necessarily confined to _mental_ phenomena; that is, "to _feelings_ or states of consciousness," and "the succession and co-existence, the likeness and unlikeness between these feelings or states of consciousness."[226] All our general notions, all our abstract ideas, are generated out of these feelings[227] by "_inseparable association_," which registers their inter-relations of recurrence, co-existence, and resemblance. The results of this inseparable association constitute at once the sum total and the absolute limit of all possible cognition. [Footnote 226: J. S. Mill, "Logic," vol. i. p. 83 (English edition).] [Footnote 227: In the language of Mill, every thing of which we are conscious is called "feeling." "Feeling, in the proper sense of the term, is a genus of which Sensation, Emotion, and Thought are the subordinate species."--"Logic," bk. i. ch. iii. § 3.]