August 7.  Three days ago (the evening before my return home) I managed to prevail upon myself to have a close and formal discussion with Harrington on the subject of his scepticism.  We had a regular fight, which lasted till midnight, and beyond.  A good deal of it was (in a double sense, perhaps) a nuktomachia.  As I had no one to jot down short-hand notes of our controversy,—­perhaps it is as well for me and for truth that there was none,—­it is impossible that I should do more than give you a succinct summary of its course.  But its principal topics are too indelibly impressed on my memory to leave me in doubt about general accuracy.

I hardly know what led to it; I believe, however, it was an observation he made on the different fates of metaphysical and physical science,—­the last all progress, and the first perpetual uncertainty.  He had been reading a remark of some philosopher who attributed this difference to the more substantial incentives offered to the cultivation of the physical sciences.  “So that,” said he, “they are, it seems, what our German friends would call ‘Brodwissenschaften’!  Not the brain, as some idly suppose, but the stomach, is the true organon of discovery, and if the metaphysician could but be punctually assured of his dinner (which has not always been the case), or at all events of a fortune, we should soon have the true theories of the Sublime and Beautiful,—­of Ethics,—­of the Infinite,—­of the Absolute,—­of Mind and Matter,—­of Liberty and Necessity; whereas I think we should only have a multiplication of doubtful theories.”

He remarked that he doubted the truth of the hypothesis in both its parts; that not the want of adequate motives, but the intrinsic difficulty of the subjects, had kept metaphysics back (on what subjects had men expended more gigantic toil?); nor, on the other hand, was it necessity that chiefly impelled man to cultivate physical science; it was the desire of knowledge,—­or rather, he added, the love of truth; for what else was his admitted curiosity, in the last resort, unless man is equally curious about falsehood and truth; “that is,” said he, laughing, “as curious after ignorance as after knowledge!  No,” he continued, “the sciences are made arts for utilitarian purposes; but the sciences themselves have a very different origin.  For my own part, I would as soon believe that Sir Isaac Newton excogitated his system of the universe in hopes of being made one day Master of the Mint.”  I assented, and, smiling, told him I was glad to find him admit that there was in man a love of knowledge, identical with the love of truth.  He said he admitted the appetite, but denied that there was always an adequate supply of food.  He admitted that in physical science man seemed capable of unlimited progress; but it seemed doubtful whether this was the case in other directions.  “What was there inconsistent with scepticism in that?” he asked.