THE ANATOMY OF SCIENCE 65 



Euclid. Postulating certain axiomatic relations between certain 

 postulated "entities" (point, line, plane, etc.), Euclid shows that de- 

 duction from the axioms yields the many relations used by the Egyp- 

 tian surveyor, and a number of other such relations not previously 

 recognized. This system thus handsomely discharges the three major 

 functions— correlative, explanatory, and heuristic— characteristic of a 

 scientific theory. Only in its comparative perfection is Euclid's ge- 

 ometry atypical of the Greek achievement. In Greek astronomical 

 theories, for example, we find again a large-scale co-ordination of 

 hitherto separate relations (used in time-keeping, navigation, calen- 

 dar-construction, eclipse-prediction, and the like), again an indication 

 of certain new relations for which to look, and again a most impres- 

 sive sense of explanation. Of this kind of achievement Margenau 

 writes : 



... a theory was born; the surface of mere correlation was broken, 

 subsurface explanation had begun. To put it another way: The con- 

 tingency of correlation had given way to logical necessity. 



Typically gratified in colligative relations like those used by the 

 Egyptian surveyor, what I call the "Egyptian desire" evokes the in- 

 tensely practical common-sense quest for order on which prediction 

 can be founded. The new element that produces science— what I call 

 the "Greek desire"— e\'okcs a search for theoretic explanation of 

 those relations, pursued urgently even when it offers no promise of 

 improving the predictive capacities with which we are already en- 

 dowed by the se\^eral relations. Far overshadowing the impressive 

 though imperfect theoretic explanations the Greeks actually propose, 

 is their first bold conception that such explanation is possible! 



The principle of intelligibility. The "Greek way" turns on a new 

 principle— distinct from those inherited by science from common 

 sense— asserting the world comprehensible by nian. Superficially 

 innocuous, this view is revolutionary.- Consider one example. Does 

 not the divinity essential in a god render that god and his activi- 

 ties incompletely intelligible to mortal men? For, says Coleridge, 

 "Incomprehensibility is as necessary an attribute of the First 

 Cause as Love, or Power, or Intelligence." Accepting the principle 

 of intelligibility we then recognize that the gods must not figure in 

 the postulates of physical theories. Expecting to find physical phe- 

 nomena intelligible, we seek to see them effects of natural (as distinct 



