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Effects of Matter
217
matters which come into contact with it. This division of prakāśa (light energy) into ātapa (warm light) and Udyota (cool light) is made on a scientific basis. The first one is preponderant in heat-rays and the second one in light-rays. According to modern physics, “heat is a form of energy and may be measured in energy units.". It may correspond to ātapa of Jaina Metaphysics, but ātapa denotes both heat and warm light.
From earlier recorded times up through the period of Newton's and Huygen's great discoverites, i. e. to about 1700, practically all thinking about the physical world was confined to the fields of mechanics and light. Prior to 1678, when Huygens studied the possibilities of a wave theory, it was commonly believed that light consists of corpuscles shooting out in straight lines from a luminous source. The ancient Greek philosophers knew such facts as the regular reflections of light at a smooth surface where the angle of reflection equals the angle of incidence; they knew qualitatively about the refraction of light at a surface separating two transparent media, such as air and water, and the apparent straight-line, or rectilinear propagation of light. All these facts could be explained quite well by a corpuscular theory'3 of Newton that light travels in a straight line. The value of the Jaina theory of ātapa and udyota lies in the fact that it touches upon both heat and light theories in a nascent form.
MODIFICATION OF MATTER Dravya (Substance) is one entity, while Dravya-Paryāya (modification of substance) is of two kinds, viz. jīvadravyaparyāya (modification of living substance) and ajsvadravyaparyāya (modification of non-living substance). There exist 1. Ta je nam puggalā sūriyassa lessaṁ phusasti te nam
puggalā sūriyassa lessam padinaṁti, Süryaprajñapti, 3.26 2. Physics, p. 248. -3. Ibid., p. 588.
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