# Logic Taught by Love/Chapter 5

CHAPTER V THE RECOVERY OF A LOST INSTRUMENT
"Hilkiah said, I have found the Book of the Law in the House of the Lord."—2 Kings xxii. 8.
To form any adequate conception of the situation in which the founders of the modern pulsation-Logic found themselves, we must imagine a state of things somewhat of this kind.
Suppose that in some social convulsion, every ophthalmoscope were now to be destroyed, and all the men who use the instrument were to perish, leaving behind a few of those who had been accustomed to see it used, and to clean or otherwise handle it. We must suppose a great many ophthalmoscope-drawings preserved, with notes proving that these purported to be drawings of the retina.
After society had settled down again, the drawings might begin to attract attention. Thereupon would set in fierce discussion in the medical world. There would be a tradition' that certain medical draughtsmen of the 19th century had a means of knowing what the living retina looks like; a means not accessible to ordinary men. Traditions would be handed down that the condition necessary for seeing how to do the drawings was induced by holding to one's eye a certain machine. These traditions would be different in form, according as the servant in whose recorded reminiscences it had originated had been accustomed to see his master use this or that form of handle or frame. It might come to be a point of faith to believe that the drawings were done while the artist was wholly or partially entranced. ​On the other hand, some sceptics would assert that the pictures were imaginary, or, at most, founded on mere observations made in the dissecting-room. More acute observers would see that something more than mere invention had been at work, and would suppose that the drawings had been the result of marvellously careful induction, made by comparing the phenomena observed in the dead eye with the symptoms of living patients. At last, in the new civilization, someone living outside the tempest of rival theories, and studying optics for himself, would re-discover the principle of the ophthalmoscope, make one, and actually see living retinas. At once he would perceive that all existing theories alike were provisional working-hypotheses, i.e., mere expressions of ignorance of the essential fact; and that the drawings of the mythical 19th century artists must have been really made by the use of just such an implement as his own.
Now, our discoverer of the future would probably be an aimable man, willing enough to share the joy of his new discovery with whoever desired to possess it; and equally willing to abstain from worrying with it persons who had no such desire. The mental condition of those who erect working-hypotheses into articles of faith, and who like consecrated theories better than Truth, would be too utterly foreign to his conceptions for him to argue with them. As for those who should desire both to retain their theories about the old drawings, and also to use the new instrument, he would consider them differentiated from ordinary lunatics only by not possessing the sincerity of the latter. He would publish an account of his discovery, for the benefit of whoever wished to read about it; and, having done so, would feel he had ​fulfilled his duty to society; and would not think himself bound to disturb himself any further.
As some readers may not be acquainted with the nature of the ophthalmoscope, I will tell my parable over again in a simpler form. Suppose there was an island, the inhabitants of which were unacquainted with the principle of numeration, and therefore could only write in numbers singly. They would be able to add and multiply numbers only so far as they could reckon. They would know what such simple numbers as "three times five" make; and very clever and persevering ones might know what twelve times twelve make. But about all large numbers they would have to guess; they would have opinions, and discuss, and generally turn out wrong. If they had a tradition among them that certain ancestors of theirs, called Moses and Isaiah, used to pronounce oracularly as to what numbers "like the trees in a forest for multitude" came to, when multiplied together, and always turned out right, they would frame a provisional working-hypothesis that Moses and Isaiah were "inspired," and would argue and jangle as to the precise nature of the " inspiration." Then suppose some islander found out how to " carry," that fortunate individual would know exactly how Moses and Isaiah made sure of their results. And of course the supporters of the rival theories about inspiration would join in calling him hard names; and equally of course he would not mind what they said, but would go on his own way, and wait till events justified his faith in Rational Arithmetic versus fanciful guesses.
Now the situation in which the modern discoverers of Mathematical Logic found themselves, was very much like that of our hypothetical new Helmholtz, or ​the island discoverer of the process of "carrying." Certain ancient Prophets had discovered a means—not of communicating with the Unseen (for every man, and woman, and child, and beast does that, until his faculties have been trampled out by the process called nowadays "Education"), but— of making communication with the Unseen safe, by applying a mechanical test to ascertain exactly what is being communicated; to distinguish, that is to say, the Inspiration of Truth from the suggestions of the diseased brain. The difference between old Scriptural and merely poetic inspiration consists precisely in the fact that the inspired men of Palestine possessed such a test. The difference between Prophecy and pseudo-prophecy in old times, consisted in applying the test with utter fidelity, in allowing it to act with mechanical accuracy. Babbage, Gratry, and Boole revived that test. They published their books. Then, finding themselves confronted with dishonest folly, they left the world to come to its senses at its leisure.