The Positive Sciences of the Ancient Hindus c6.6

c6.6

*Nyâya-Vaiśeṣika.*—The early Nyâya writers hold that the sound-wave (शब्दसन्तान) has its substrate in Âkâśa (ether) and not Vâyu (air). Later writers (*e.g.* Vâchaspati in the Tattvavindu) add that sound itself as a phenomenon is not to be conceived as a mode of motion (*parispanda*), for Âkâśa, the substrate, is, in the Nyâya view, incapable of motion (न तावत् परिस्पन्दस्तस्य मूर्त्तनुविधायिनो द्रव्ये विभुनि विभुगुणे वा शब्दे मूर्त्तभावेनासम्भवात्—Tattvavindu). At the same time the propagation of sound must be conceived on the analogy of waves in water (वीचितरङ्गन्याय). Udyotakara in the Vârtika, Vâchaspati in the Tâtparyyaṭîkâ, and Jayanta in the Nyâya-Manjarî controvert the three views current in the Mîmâmsâ school—(1) that Nâda, the physical basis of audible sound, is a specific quality of Vâyu (air), (2) that sound, in its physical aspect, is constituted by a series of air movements of the nature of a current (वायुसन्तान), and (3) that it is not air-currents but air-waves, series of conjunctions and disjunctions of the air-particles or molecules (वाय्ववयवाः, वायुपरमाणवः), that constitute the Nâda, the sound physical, to which, in the case of significant sounds, the Mîmâmsakas assign the function of manifesting the Sphoṭa, "transcendental" or "intelligible" sound (*logos*, the word). *Vide* Udyotakara Vârtika, Adhyâya 2, Âhnika 2, Sûtra 14; also Tâtparyyaṭîkâ, माभूत् वायुसन्तानो मा च भूततद्गुणो नादः शब्दस्य व्यञ्जकः वायवीयास्तु संयोगविभागव्यञ्जका भवन्ति इत्यतआह, etc., *loc. cit.* Against these views the early Nyâya doctors maintain that sound is a specific quality of Âkâśa (ether) and not of Vâyu (air). At the same time they admit that the impact which originates the sound phenomenon (अव्याप्यवृत्ति अयावद्द्रव्यभावि विशेषगुण) in Âkâśa does so by setting up a vibration in the molecules of the object struck (*e.g.* a bell), and that these vibrating molecules impinge against the air-molecules in contact (वायुपरमाणवः, प्रत्यासन्नवायुः). In other words, though Âkâśa is the substrate (आश्रय), the efficient cause of sound (निमित्तकारण) is to be found in the mechanical impact (अभिघात) of vibrating molecules of sonorous bodies against contiguous molecules of air. As to the propagation of sound, the early Nyâya-Vaiśeṣika writers content themselves with stating that the first sound thus produced in the substrate Âkâśa by the impact of the vibrating molecules (*e.g.* of a bell) against the contiguous molecules of air, produces a second sound in the contiguous Âkâśa, and the second sound a third, and so on, in the same way as waves are generated in water, until the last sound sets up a vibration in the ear-drum (कर्णशष्कुलि). Of course, this propagation of sound-wave in Âkâśa (ether) is effected by means of the air-wave as its vehicle. This is the Nyâya-Vaiśeṣika hypothesis (कल्पना) of an independent sound-wave (शब्द-सन्तान). Âkâśa (ether) is motionless, but the air-wave would not be transmitted if the air-molecules were not interconnected by Âkâśa. Praśastapâda, the Vaiśeṣika doctor, for example, describes the first sound as giving off a second, the second a third, and so on, expanding in Âkâśa, in the same way as waves are supposed to propagate themselves in the ocean.