IN ZALT-BOMMEL 

London, 14 April 1864 
1 Modena Villas, 
Haverstock Hill, N.W. 

Dear Uncle, 

I hope that the cough has gone the way of all flesh. As for 
myself, there hasn’t been a sign of a ruruncie for a few days, and 
my doctor‘ thinks that I am now rid of the things for good. And 
high time, too. The sun seems to be breaking through at last. But 
there’s still a nasty wind blowing from the East. Eleanor’s cough 
has gone. However, her sister Jenny has a very persistent cough, 
[which] will disappear [only] with a change of wind. 

Conradi had already written to me before I got your letter, and 
I had replied, saying he could send the money here direct.* 

At the Museum! I have been taking a look at Boethius’s De 
arithmetica (he wrote at the time of the Völkerwanderung) on 
Roman division (he didn’t, of course, know any other sort). From 
this and a number of other works with which I have compared it, 
I see that moderately simple calculations, such as household and 
commercial accounts, were never done with [figures] but with 
pebbles and similar tokens on an abacus. On this abacus several 

4 Karl Philips - > Jean Philips - © Allen - 4 Manuscript damaged. - ¢ See this vol- 
ume, p. 501. - f the British Museum Library 

parallel lines were drawn and whatever was used, whether pebbles 
or other visual signs, denoted units on the first line, tens on the 
second, hundreds on the third, thousands on the fourth, etc. Such 
abacuses were in use throughout almost the whole of the Middle 
Ages and are still employed by the Chinese today. As for more 
complex mathematical calculations, at the time when these are 
found among the Romans, the latter already had the multiplica- 
tion table— Pythagoras’s—which, however, was still very awkward 
and cumbersome, for that table consisted partly of its own 
characters, partly of letters of the [Greek (later Roman) alphabet. 
But [since] division merely boils down to the analysis of the 
dividend into factors and the tables in question were taken to 
fairly high figures, this must have sufficed for the reduction of 
expressions such as MDXL, etc. Every number, e.g. M, was 
separately reduced to the factors which it formed with the divisor, 
after which the quotients were added together. Thus, for example, 
M divided [by] two=D (500), D divided by 2=250 e[tc]. That the 
ancient method placed insuperable difficulties in the way of very 
complex calculations is evident from the artifices to which that 
outstanding mathematician Archimedes had recourse. 

As regards the ‘darkness of outer space’, this necessarily follows 
from the theory of light. Since colours only appear when 
light-waves are reflected by solids and since, in the intervals 
between the heavenly bodies, there is neither atmosphere nor any 
other kind of solid, these intervals must be pitch black. They allow 
the whole light-ray to pass through, which is simply another way 
of saying that they are dark. Moreover, space outside the 
atmosphere of the planets, etc., is fated to be damnably ‘koud en 
kil™ since the rays generate warmth only when they strike a solid, 
which is also why, summer or winter, it is icy cold in the higher air 
strata of our atmosphere—that is, owing to the thinness, hence 
the relative insubstantiality, of these layers. But 

Ought this affliction to afflict us 
Since it but adds to our delight?> 

And what good are light and warmth were 1THERE Is NO EYE TO SEE 
THE ONE, AND NO ORGANIC MATTER TO FEEL THE OTHER? Long ago the worthy 
Epicurus had the sensible idea of banishing the gods to the 
intermundia (i.e. the empty spaces of the universe)”*' and, indeed, 
R.’s‘ ‘perfect curs’ are fit denizens for those cold, cool, pitch dark, 

ad 

‘stoffelooze wereldruimte’. 

@ icy cold-> From Goethe’s West-östlicher Diwan (‘An Suleika’). - © Probably 
Roodhujzen’s. - 4 spaces devoid of matter 

You can see what a good Dutchman I’ve become from the fact 
that little Jenny has already read half the Camera obscura* and 
Laura, me docente, a large part oF THE FIRST VOLUME oF THE Aardrijks- 
kunde, while even Eleanor knows ‘Dans Nonneken dans’ and 
‘Klompertjen en zijn wijfjen” by heart. 

Best compliments from tHe whole FAMILY to you, and Karl, not 
forgetting madame la générale“ With the weather being so fine, you 
surely won’t have overlong to wait for your own beau jour! 

Your affectionate nephew, 
Karl Marx