B O O K R E V I E W

Lucio Russo: L’America dimenticata. I rapporti tra le civiltà e un
errore di Tolomeo

Mondadori Università, Milan, 2013

Liliana Curcio

Published online: 18 July 2014

� Centro P.RI.ST.EM, Università Commerciale Luigi Bocconi 2014

Why did the celebrated Ptolemy (ca. 100–170 AD)

commit a macroscopic error in measuring the dimensions

of the earth, while Eratosthenes of Cyrene (ca. 275–195

BC), several centuries earlier, had calculated the same

measurement with an almost exact result (with a deviation

of less than 1 % from the actual known dimension)?

This question, apparently of interest only to mathema-

ticians, cartographers and geographers, becomes the point

of departure for a fascinating investigation that gives rise to

unexpected suppositions. In fact, Lucio Russo maintains

the surprising hypothesis that the reason for Ptolemy’s

error lies in the collapse of knowledge that followed the

Roman conquests. According to this theory, the broadening

of territories conquered by Rome went hand-in-hand with a

systematic destruction of the culture of all peoples con-

quered. One example is sufficient: the destruction of the

Library of Alexandria and its inestimable patrimony of

codices and volumes containing the entirety of human

knowledge. In Russo’s words:

This was not only the largest collection of books in

existence in the world, but also the most important

centre of editorial production, closely connected to

the Musaeum of Alexandria, that is, to the principal

public research institution of the ancient world, where

scholars were lived at the expense of the state,

devoting themselves to their own work without

material worries (p. 90, our trans.).

The loss of knowledge was not limited to the scientific

methodologies of mathematical geography and cartogra-

phy, but also regarded the information about places and

peoples, which often dated back to much earlier epochs.

The recollections of past journeys also gradually disap-

peared, leaving in their wake tales that were legendary and

unbelievable.

All of this is addressed in the book, starting with a

mathematical key, a problem tied to mathematical geog-

raphy: Ptolemy’s error. With refined accuracy, Lucio Russo

L. Curcio (&)
Largo Vulci 9, 20159 Milan, Italy

e-mail: liliana.curcio@unibocconi.it

123

Lett Mat Int (2014) 2:111–112

DOI 10.1007/s40329-014-0053-1



examines the routes taken and the inconsistencies of the

results achieved by different scholars from Eratosthenes to

Hipparchus all the way to Ptolemy.

The measurements of the scientists were made on the

basis of tables previously compiled. Eratosthenes, who was

director of the Library of Alexandria, used a procedure

based on calculations within the framework of a mathe-

matical model.

Ptolemy’s error is due to a dilatation of the length in

longitude, the consequence of which is a decrease in the

size of the earth: 180,000 stadia for the length of the cir-

cumference instead of the 252,000 stadia obtained by

Eratosthenes, which was much closer to the actual mea-

surement. What is astonishing is that the dilatation of

longitudes and the contraction of the dimensions of the

earth are both aspects of the same error. While the latitudes

of many localities are taken from direct sources and thus do

not lead to the introduction of errors, the information

available at the time regarding longitude required complex

elaboration, and hence the error: the ‘Fortunate Islands’

that Ptolemy identified with the Canary Islands actually

correspond to the Lesser Antilles (more precisely, the so-

called Leeward Islands: the Americas!). The identification

of the Fortunate Islands with the Canaries resulted in a

chain of errors, leading Ptolemy to miscalculate the scale

of longitudes and consequentially, to reduce the dimen-

sions of the earth. From all of this it can be deduced that in

the second century BC (and perhaps even earlier) the ships

of the Mediterranean, and probably first of all those of the

Carthaginians, not only reached the Caribbean but opened a

route that was then used continuously. This would explain

various of what appear to be historical inconsistencies,

such as the representations of fruits that appear undoubt-

edly to be pineapples (a fruit native to the Antilles) in the

works of artists and painters, and, in the opposite direction,

the presence in the Americas of chickens, fowls of Eurasian

origin, found by Christopher Columbus when he landed

there.

Lucio Russo’s hypothesis is fascinating, one that leads

to deeper reflection and perhaps even to a revision of his-

tory books. It also leads us to consider the possibility that

human societies arrive at the same results at the same time

in very distant contexts, not by a kind of ‘convergent

evolution’, but because they are mutually connected in a

network of cultural exchanges and knowledge.

Translated from the Italian by Kim Williams.

Liliana Curcio teaches mathe-
matical analysis at the Politec-

nico di Milano. Formerly she

taught mathematics and physics

at the Istituto Statale d’Arte

sperimentale (ISA) in Monza.

She is a collaborator with the

Centro Pristem, coordinating the

courses of ‘mathematical orien-

tation’ (Orientamatica) dedi-

cated to high school students.

She is a member of the Editorial

Board of the Lettera Matemati-

ca, to which she has contributed

various articles, with particular

regard to the connections between mathematics, art and architecture.

112 Lett Mat Int (2014) 2:111–112

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	Lucio Russo: L’America dimenticata. I rapporti tra le civiltà e un errore di Tolomeo
	Mondadori Università, Milan, 2013