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power ? The limits of the one will be found to be coincident 
with those of the other. 
Here let me draw attention to the distinction, often over- 
looked, between our powers of comprehension and dis- 
covery. We may be perfectly able to comprehend a thing 
after it has been discovered, but may be wholly or partially 
unable to make the discovery itself. For example, I may 
he quite able to comprehend Euclid now that all its various 
truths have been reasoned out, but quite unable, from the 
definitions, postulates, and axioms alone, to have reasoned 
out the entire system of geometry which it contains. The 
disregard of this obvious distinction is one of the grounds 
on which F. Newman has asserted the impossibility of a 
moral revelation. 
In bringing this subject to your notice, I cannot help 
alluding to the controversy between Sir W. Hamilton, Mangel, 
and Mill, on the limits of thought. I shall enter on the 
subject only as far as is required by the exigencies of the 
present inquiry. I am aware that Professor Kirk has 
already partially discussed this subject, but with a wholly 
different purpose from my own, in a former paper. With 
some of his conclusions I agree; with others I am unable 
to concur ; while some of them have nothing to do with my 
present inquiry. My general conclusion, on a review of the 
whole controversy, is, that the limits of rational and religious 
thought are the same. 
The subject of debate has been much darkened by its 
having been discussed in an abstract rather than in a 
concrete form. The question in debate is, Can we form 
a true conception of the Infinite ? Throwing aside the 
abstract form of the question, if I understand Dean Mansel 
rightly, he maintains that our conceptions of the infinite 
perfections of Deity are only true analogously and relatively ; 
and that all attempts to reason on the infinite involve us in 
hopeless contradictions. Mr. Mill, on the contrary, asserts 
that our conceptions of the divine attributes must be abso- 
lute though imperfect truth ; and that our finite conceptions, 
as far as they go, are correct though imperfect measures of 
the infinite. He argues that to require a man to believe in 
an attribute of Deity, the true nature of which he cannot 
comprehend, is a hopeless absurdity. 
My own opinion is that there is a considerable amount of 
truth on both sides of the controversy. That portion of 
Manseks argument is quite sufficient for my purpose which 
shows that all our attempts to reason on a number of high, 
transcendental conceptions, involve us in hopeless contra- 
