But the man of science, who, forgetting the limits of philosophical inquiry, slides from these formulae and symbols into what is commonly understood by materialism, seems to me to place himself on a level with the mathematician, who should mistake the _x_'s and _y_'s, with which he works his problems, for real entities--and with this further disadvantage, as compared with the mathematician, that the blunders of the latter are of no practical consequence, while the errors of systematic materialism may paralyse the energies and destroy the beauty of a life. FOOTNOTES: [10] The substance of this paper was contained in a discourse which was delivered in Edinburgh on the evening of Sunday, the 8th of November, 1868--being the first of a series of Sunday evening addresses upon non-theological topics, instituted by the Rev. J. Cranbrook. Some phrases, which could possess only a transitory and local interest, have been omitted; instead of the newspaper report of the Archbishop of York's address, his Grace's subsequently-published pamphlet "On the Limits of Philosophical Inquiry" is quoted; and I have, here and there, endeavoured to express my meaning more fully and clearly than I seem to have done in speaking--if I may judge by sundry criticisms upon what I am supposed to have said, which have appeared. But in substance, and, so far as my recollection serves, in form, what is here written corresponds with what was there said. [11] "The Limits of Philosophical Inquiry," pp. 4 and 5. [12] Hume's Essay "Of the Academical or Sceptical Philosophy," in the "Inquiry concerning the Human Understanding." VIII. THE SCIENTIFIC ASPECTS OF POSITIVISM.