BR TO C.P. SANGER, 29 SEPT. 1894
BRACERS 55927. ALS. McMaster. SLBR 1: #50
Edited by N. Griffin. Proofread by A. Duncan and K. Blackwell

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Sep. 29. 1894

Dear Sanger

I was very glad of your letter, but much alarmed at your 3 conundrums. I hope in time to be able to give some sort of answer to them, but as yet I have only had to copy dispatches and cyphers and decypher telegrams from which one doesn’t learn much. However when people come back to Paris I shall see something of French politicians, and then I hope to find out something. I have an introduction to M. Ribot,1 who used to be foreign minister — you might give me a brief account of the prominent facts about him, which you probably know by heart; also to a man whose prominent interest is the Income Tax, which he wants to introduce in France.2 If you could send me some pamphlet on it or tell me how to get it up before seeing him, I should be deeply grateful. — Now for a connundrum on shop: You I believe possess a complete Euclid — would you mind telling me if in Bk. XI or elsewhere there is any comparison of volumes and if so, whether this is effected by Congruence and superposition and the axiom about it (axiom 8 or 10 I think). I don’t know of any other way of establishing Geometrical Equality, but in I.4 it is always said to involve the 3rd Dimension, and in this case its use for solids would involve the 4th. I see no alternative to congruence but the Identity of Indiscernibles, which is not very geometrical. Do tell me how e.g. it is proved that 2 cubes, each of unit side, are equal. I am quite in a fix. Tell me also if you know of any other way of establishing Geomal. Equality besides Congruence. To me it seems to have no meaning except possible Congruence. — I think I may be able, towards the end of Oct., to come over a Sat. to Monday — if so I will write a paper. If Trotter3 still wants a paper for the M.S. Club, I would perhaps write him one on Space and Geometry, which perhaps you would read. But only if he is still badly in want of a paper. My present view is that Euc. has the same superiority over Metageometry4 that Kepler has over Epicycles — both seem possible ways of accounting for the given sensations, but the former in each case is the simpler. Const. measure of curvature on the contrary is I think an à priori necessity of thought, in the sense that its denial involves philosophic absurdities such as absolute position.

I’m more contented now than I was — I get a certain amount of my own work done, and I ride a bicycle, which is a great score. I’ve made the acquaintance of Whistler,5 having an introduction to him from the Pearsall Smiths, which is also a score. And later on, when there are more people in Paris, I dare say I shall have a comparatively good time. But I’ve seldom been more lonely and dreary than my 1st fortnight here — away from everything and everybody I cared for.

Yours frat.
Bertrand Russell.

• 1

  M. Ribot Alexandre Ribot (1842–1923), a Republican deputy. He was Minister of Foreign Affairs from 1890 to 1893.

• 2

  a man whose prominent interest is the Income Tax … France Probably Jacques Cavaignac, a Republican deputy.

• 3

  Trotter W.H. Trotter, secretary of the Cambridge Moral Sciences Club. Sanger read the paper BR proposed on 9 November 1894.

• 4

  Metageometry Non-Euclidean geometry. BR contrasts Kepler’s heliocentric model of the solar system with the Ptolemaic model in which the earth is at the centre of the solar system and the other bodies revolve around it. The apparent, occasional backwards motion of the planets in their orbits was explained on the Ptolemaic model by the addition of the epicycles, but the motion needed no such ad hoc device on the Keplerian model.

• 5

  Whistler The American painter. BR had called on him the previous day. Logan knew him quite well.