4. (_Mr. Mansel_)--But the most important of my critics on this ground is Mr. Mansel, who has revived the censure of my speculations as not doing justice to the Kantian philosophy. "It is much to be regretted," he says[310], "that Dr. Whewell, who has made good use of Kantian principles in many parts of his _Philosophy of the Inductive Sciences_," has not more accurately observed Kant's distinction between the necessary laws under which all men think, and the contingent laws under which certain men think of certain things. And further on Mr. Mansel, after giving great praise to the general spirit of the _Philosophy of the Inductive Sciences_, says, "It is to be regretted that the accuracy of his theory has been in so many instances vitiated by a stumble at the threshold of the Critical Philosophy." Mr. Mansel is, indeed, by much the most zealous English Kantian whose writings I have seen;--among those, I mean, who have brought original powers of philosophical thought to bear upon such subjects; and have not been, as some have been, enslaved by an admiration of German systems, just as bigotted as the contempt of them which others feel. And as Mr. Mansel has stated distinctly some of the points in which he conceives that I have erred in deviating from the doctrines of Kant, I should wish to make a few remarks on those points. 5. Kant considers that Space and Time are conditions of perception, and hence sources of necessary and universal truth. Dr. Whewell agrees with Kant in placing in the mind certain sources of necessary truth; he calls these Fundamental Ideas, and reckons, besides Space and Time, others, as Cause, Likeness, Substance, and several more. Mr. Mill, the most recent and able expounder of the opposite doctrine, derives all truths from Observation, and denies that there is such a separate source of truth as Ideas. Mr. Mansel does not agree either with Mr. Mill or Dr. Whewell; he adheres to the original Kantian thesis, that Space and Time are sources of necessary truths, but denies the office to the other Fundamental Ideas of Dr. Whewell. In reading what has been said by Mr. Mill, Mr. Mansel, and other critics, on the subject of what I have called _Fundamental Ideas_, I am led to perceive that I have expressed myself incautiously, with regard to the identity of character between the first two of these Fundamental Ideas, namely, Space and Time, and the others, as Force, Composition, and the like. And I am desirous of explaining, to those who take an interest in these speculations, how far I claim for the other Fundamental Ideas the same character and attributes as for Space and Time.