is at new or full, and slowest at the first and third quarter,
was rediscovered by Tycho Brahe six centuries later; a fact which
in itself evidences the neglect of the Arabian astronomer's
discovery by his immediate successors.

In the ninth and tenth centuries the Arabian city of Cordova, in
Spain, was another important centre of scientific influence.
There was a library of several hundred thousand volumes here, and
a college where mathematics and astronomy were taught. Granada,
Toledo, and Salamanca were also important centres, to which
students flocked from western Europe. It was the proximity of
these Arabian centres that stimulated the scientific interests of
Alfonso X. of Castile, at whose instance the celebrated Alfonsine
tables were constructed. A familiar story records that Alfonso,
pondering the complications of the Ptolemaic cycles and
epicycles, was led to remark that, had he been consulted at the
time of creation, he could have suggested a much better and
simpler plan for the universe. Some centuries were to elapse
before Copernicus was to show that it was not the plan of the
universe, but man's interpretation of it, that was at fault.

Another royal personage who came under Arabian influence was
Frederick II. of Sicily--the "Wonder of the World," as he was
called by his contemporaries. The Almagest of Ptolemy was
translated into Latin at his instance, being introduced to the
Western world through this curious channel. At this time it
became quite usual for the Italian and Spanish scholars to
understand Arabic although they were totally ignorant of Greek.

In the field of physical science one of the most important of the