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62
'
,
,
(ot)
ON ASTRONOMERS
THIRD DISCOURSE.
(? /// Z,0f 0/ /** Stars and the excellence of the ^Astronomer in
(
Abu Rayhan
that Science.
of his
(Kitdbut- Tafhim
1
al-Biruni says, in the first chapter
"
Explanation of the "
Scjence of Astronomy
ft sind'ati't-TanjimY: "A man doth not merit the title of
Astronomer until he hath attained proficiency in four sciences ;
first, Geometry ; secondly, Arithmetic ; thirdly, Cosmography ;
and fourthly, Judicial Astrology."
Now Geometry is that science whereby are known the dispositions
of lines and the shapes of plane surfaces and solid
bodies, the general relations existing between determinates and
determinants, and the relation between them and what has
are included in the book of
position and v form. Its principles
Euclid the Geometrician 3 in the recension of Thabit ibn Qurra 4 .
Arithmetic is that science whereby are known the nature of all
sorts of numbers, especially each species thereof in itself; the<
nature of their relation to one another ; their generation from
each other ;
and the applications thereof, such as halving, doubling,
multiplication, division, addition, subtraction, and Algebra. The
principles thereof are contained in the book of the 'Aptd^ijTiKij,
and the applications in the "Supplement" (Takmila) of Abu
5
Mansur of Baghdad and the ,
" Hundred Chapters" (Sad Bdb)
of as-Sajzi 6 .
Cosmography is that science whereby
are known the nature of
the Celestial and Terrestrial Bodies, their shapes and positions,
their relations to one* another, and the measurements and distances
which are between them, together with the nature of the
movements of the stars and heavens, and the co-ordination of
the spheres and segments whereby these movements are fulfilled.
c
o
1 The best account of this great scholar is that given by Dr Edward Sachau in the
. ^German Introduction to his edition of al- Athdru' I- Bdqiya (Leipzig, 1876), and, in a
shorter form, in his English translation of the same (London,* 1879). The substance of
this is given by Mirza Muhammad on pp. \1V-. ^Y of the Persian notes. See Note
XXIII at the end.
2 This book was composed simultaneously in Arabic and Persian In A.H. 420
(A.D. 1029). There is ? fine old MS. of the Persian version dated A.H. 68j (A.D. 1286),
and bearing the class-mark Add. 7697, in the British Museum. See RiSeu's Persian
Catalogue, pp. 451-452. ,,
3 Najjdr, literally, "the Carpenter."
4 I take this to be the sense of 'C^~l *>j* IK*-''* *>* O^ *Z*J& *s .
Concerning Thabit ibn Qurra, see Wiistenfeld's Gesch. d. Arabischen Aerzle, pp'. 34-36 ;
Brockelmann's Gesch. d. Arab. Litteratur, vol. i, pp. 217-218, etc. He was born in
A.H. 221 (A.D. 836) and died in A.H. 288 ,
(A.D. 901).
5
Abu" Mansur 'Abdu'l-Qahir ibn Tahir al-Baghdadi, d. A.H. 429 (A.D. 1037^ See
Hani Khalifa, No. 3253.
***
* Abii Sa'id Ahmad ibn Muhammad ibn 'Abdu'l-Jalil as-Sajzi {oroSijazi, i.e. of
Sajistan or Sistan). See Brockeimann, op. cit., vol. i, p. 219, and Note XXlfl at
the end.