OUR OBLIGATIONS TO GREEK THOUGHT. 229 
Archimedes is to be ascribed the discovery of the principle of the 
lever, as also the hydrostatical law relating to the condition of 
floating bodies.* Optical science began in Euclid’s detecting the 
law of the reflection of light.t Galileo himself declares that he 
found in Aristotle the principle of “ virtual velocities.”” Of course, 
astronomy in some form was cultivated by the Orientals; but it is 
to the Greeks we owe some of the important truths on which 
subsequent astronomy has proceeded; for while, according to 
Pliny, Anaximander, and, according to Plutarch, Pythagoras pointed 
out the obliquity of the sun’s course amongst the stars,{ Aristotle’s 
own argument in his De Celo, ii. 14, proves, to use his own words, 
‘that the earth is not only spherical, but is not large, compared 
with the magnitude of other stars.”’? Nor is this all; for on the 
basis of the doctrine of the phases of the moon, as suggested by 
Anaximander, and reasserted by Aristotle, Aristarchus of Samos 
(280 B.c.) even essayed to obtain a measure of the distance of the 
sun as compared with the moon—displaying, for the age, an energy 
of mind surpassed only some one hundred and fifteen years later 
by Hipparchus in the establishment of the theory of eccentrics and 
epicycles.§ 
Now, as compared with the wonderful development of the various 
physical sciences within the past hundred years, these products of 
Greek thought may seem insignificant; but at all events we have 
inherited the results of these early labours, and owe to them the 
beginnings on which we have continuously improved. 
Turning away from the sciences, let us attend for a few minutes 
to the processes by which scientific knowledge is acquired and its 
principles subsequently applied in form of argument. With certain 
reservations, hereafter to be noticed, I think it may be affirmed as 
a matter of historical fact, that we owe to the Greeks the method 
by which our modern science has achieved its wonderful success ; 
as, also, the logical forms by the use of which the results of our 
Inductions are deductively employed in the elaboration of system- 
atised knowledge. We live in an age of Induction, when men are 
eager for particular facts, and resent any formulated hypothesis 
which cannot be attained by a cautious ascent from the particular 
to the universal, or which is incapable of verification by well 
* Whewell, “ Hist. Induct. Sciences,” i. p. 95. 
¢ Ibid, p. 98. t Ibid, pp. 142-3. 
§ Whewell, “Hist. Induct. Sciences, i. pp. 151-5, 179. 
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