In Ptolemy’s maps, Columbus saw his destiny

In Ptolemy’s maps, Columbus saw his destiny

The map of the known world from Ptolemy's "Geography"

Originally published 12 October 1992

In mid-Feb­ru­ary 1493, Christo­pher Colum­bus’ ships, the Niña and the Pin­ta, neared the Azores on their return jour­ney from the New World. The flag­ship, San­ta Maria, had been wrecked on the shore of what is now Haiti, and Colum­bus had left some of his crew behind at a place he called Navidad.

A severe storm swept the lit­tle fleet, the worst the sailors had ever expe­ri­enced. Fear­ing that his ships would founder, and that news of his voy­age might be lost for­ev­er, Colum­bus wrote on parch­ment an account of his dis­cov­er­ies, wrapped it in water­proof waxed cloth, sealed it into a cask, and tossed it into the sea, in the hope that it might wash up on some Euro­pean shore.

The ships sur­vived the storm. The admi­ral made his report in per­son to his sov­er­eigns, the King and Queen of Spain. The dis­cov­ery of the New World became the cen­tral, trans­form­ing event of West­ern civilization.

As far as we know, the sealed cask was nev­er found. What if the ships had gone down? The crew­men left behind at Navi­dad were slaugh­tered by Indi­ans, so there was no chance that they might have some­how built a boat and returned to Spain. Colum­bus and his lit­tle fleet would have sailed into oblivion.

If Colum­bus had not returned, a chill­ing effect would have been cast over oth­er would-be dis­cov­er­ers, and mon­archs might have been reluc­tant to throw good mon­ey after bad. But two things made it inevitable that the dis­cov­ery of Amer­i­ca would not have been long delayed for long: the Geog­ra­phy of Claudius Ptole­my, and the inven­tion of printing.

Scarce­ly any­thing is known of Ptole­my the man. He lived in the first half of the sec­ond cen­tu­ry A. D., more than 13 cen­turies before Colum­bus. He seems to have done most of his sci­en­tif­ic work at Alexan­dria in Egypt. He was a man of wide inter­ests and order­ly mind, who wrote books on geog­ra­phy, astron­o­my, music, and optics. That’s it. Remark­ably lit­tle can be said about the man who made the dis­cov­ery of Amer­i­ca at the time of Colum­bus inevitable.

It is sig­nif­i­cant that Ptole­my lived at Alexan­dria. That city had long been a cen­ter for the study of the Earth and sky, and Ptole­my was heir to the accu­mu­lat­ed knowl­edge of his pre­de­ces­sors. It was a place won­der­ful­ly suit­ed for a geo­g­ra­ph­er: Alexan­dria was a thriv­ing com­mer­cial cen­ter, a gath­er­ing place for ships and car­a­vans from all over the known world.

Ptole­my’s Geog­ra­phy con­sist­ed of an atlas of 27 maps, includ­ing a map of the known world, and exten­sive text. It is the only car­to­graph­i­cal work to sur­vive from antiq­ui­ty. Almost every con­ven­tion map­mak­ers use today, includ­ing lines of lat­i­tude and lon­gi­tude, curved pro­jec­tions with north at the top, and ways of delin­eat­ing the bound­aries between land and sea, rivers, moun­tains, and towns, derive from Ptolemy.

Euro­peans learned of Ptole­my’s work from man­u­scripts import­ed from the east­ern Mediter­ranean ear­ly in Colum­bus’s cen­tu­ry. The first print­ed edi­tion appeared in 1472, not long after the inven­tion of print­ing by Guten­berg. Oth­er edi­tions quick­ly fol­lowed, and Ptole­my’s atlas became wide­ly dis­trib­uted through­out Europe.

The maps were a rev­e­la­tion. They fired imag­i­na­tions. For the first time in a thou­sand years, Euro­peans held in their hands a vivid rep­re­sen­ta­tion of a spher­i­cal earth. Colum­bus saw the maps of Ptole­my, and knew his des­tiny. If he had not returned from his voy­age to the Indies, the maps assured that oth­ers would have fol­lowed soon.

How did Ptole­my’s maps sur­vive, vir­tu­al­ly unchanged, for more than a thou­sand years, in a time of hand-copied man­u­scripts. The answer, I think, has to do with what is Ptole­my’s great­est con­tri­bu­tion to sci­ence — a con­tri­bu­tion even greater than the maps that inspired Columbus.

Ptole­my was the first to describe the earth and sky with­out ref­er­ence to human cul­ture. His maps includ­ed none of the embell­ish­ments that found their way onto so many oth­er rep­re­sen­ta­tions of the world, before and after Colum­bus — no gods or god­dess­es, reli­gious sym­bol­ism, kings and queens, ships, fish, or mon­sters. His goal was descrip­tion, or as he called it, “sav­ing the appear­ances,” with math­e­mat­i­cal sim­plic­i­ty and as much fideli­ty to expe­ri­ence as possible.

His maps sur­vived pre­cise­ly because of their objec­tiv­i­ty. They posed no threat to reli­gious or polit­i­cal ortho­dox­ies. They made no claim to Ulti­mate Truth. They were accom­pa­nied by instruc­tions on how they might be amend­ed as new expe­ri­ence warranted.

In all of this, Ptole­my was close to the spir­it of mod­ern science.

Medieval Euro­pean maps placed Jerusalem at the cen­ter, and Eden (the East) at the top, with the con­ti­nents laid out in the form of the cross of Christ. The only moun­tains delin­eat­ed on some maps were Sinai and Cal­vary. Such maps had their pur­pose in the cul­ture of their time, but they would hard­ly have inspired a mariner to set out across the west­ern ocean.

Ptole­my’s maps inspired the con­fi­dence that made such a voy­age inevitable. They were sci­en­tif­ic in the best mod­ern sense of the world. They pre­sent­ed a the­o­ry — of a spher­i­cal Earth of sail­able dimen­sion — that inspired a gen­er­a­tion of Euro­peans. Colum­bus’s voy­age can be thought of as a sci­en­tif­ic exper­i­ment con­trived to prove the theory.

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