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The Positive Sciences of the Ancient Hindus c5.s2: Section 2. Motion Considered in Relation to its Causes

The Positive Sciences of the Ancient Hindus c5.s2

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Section 2. Motion Considered in Relation to its Causes

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Various kinds of motion are observed:—

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I. Movements which are not caused by contact with matter:—

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(1) Movements caused by volition (प्रयत्न), *e.g.* the movement of the hand.

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(2) Movement as of a falling body. This is caused by gravity (गुरुत्व), which in the astronomical treatises of Âryabhata, Brahmagupta, and Bhâskara is ascribed to the attraction (आकर्षण, pulling force) exercised by the earth on a material body. The force of gravity may be counteracted by volition (विधारकप्रयत्न), as in holding up the hand, or by contact, as when a body rests on a support, or by Vega (वेग), impressed motion, as in the flying arrow which is kept from falling by the motion impressed on it.

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(3) Motion of fluids, as the downward flow in a stream (स्यन्दन). This is due to fluidity (द्रवत्व), which is a characteristic property of certain kinds of atoms, in some cases original, in others produced by the contact of these atoms with the atomic particles of heat (*e.g.* in the fire). But Śaṅkara Miśra points out that this property, fluidity, is only a concomitant condition (असमवायिकारण); the efficient cause (निमित्तकारण) is even in this case gravity (गुरुत्व) in the particles of the fluid. यत्प्रदूरसंसरखं स्यन्दनं तत् द्रवत्वात् असमवायिकारणात् उत्पद्यते, गुरुत्वात् निमित्तकारणात् असमवायिकारणेषु (Śaṅkara Miśra, Upaskâra, on Sûtra 4, Âhnika 2, Chap. V., of the Vaiśeṣika Sûtras).

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(4) Certain motions, not due to material contact, of which the mechanical causes are unknown, and which may be ascribed to the universal final cause, Adṛiṣṭa (अदृष्ट), *e.g.* the first motion in atoms at the beginning of Creation, the upward motion of fiery particles or atoms, and the oblique motion of gaseous particles, *vâyu* (वायु), the movement of iron towards the magnet, capillary motion (अभिसर्पण) as of liquid particles from the root to the stem of a plant. The upward motions (चारोहण) of water-particles in evaporation and in boiling do not require the hypothesis of Adṛiṣṭa, as these are caused by the pressure of heat-corpuscles (तेजः परमाणु) and the contact with air-particles (नोदनापीड़नात् संयुक्तसंयोगाच्च—Vaiśeṣika Sûtra, Chap. V., Âhnika 2).

Meaning of Adriṣṭa (अदृष्ट)

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*Adṛiṣṭa* (*lit.* unseen) stands for "unknown cause" or "unexplained Nature" in the earlier Vaiśeṣika writers. Several classes of cases falling under Adṛiṣṭa are distinguished, *e.g.*—

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(1) The operation of merit and demerit (धर्म and अधर्म), a transcendental cause, which has to be posited in explaining the conjunctions and disjunctions of souls with their organic vehicles (bodies), which cannot be ascribed to natural causes, but presuppose the law of Karma, or the operation of moral causation, as superimposed on the natural order.

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(2) Various kinds of motion in the different classes of elements, *e.g.* their natural modes of operation, such as the dispersion of *vâyu* (air, gas), the upward motion of fire, the attraction of the needle by the magnet, etc., motions which serve the ends of Creation and of created beings (उपकारकं अपकारकं). Such natural properties must be ascribed to Adṛiṣṭa, final causality (उपकारापकारसमर्थं अदृष्टकारितं), provided the cause cannot be ascertained by *observation or inference.*

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¹ इष्टप्रवृत्तिभ्याम् धर्माधर्माभ्याम् कर्मात्पद्यते—*Ibid.* अपसर्पणकर्म उपसर्पणकर्म, etc.

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² एवमन्यदपि महाभूतेषु यत्प्रत्यक्षानुमानाभ्यामनुपलभ्यमानकारणं उपकारापकारसमर्थं च भवति तदपि अदृष्टकारितं—*Ibid.*

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Jayanta in the Nyâya-Manjarî notes that Adṛiṣṭa is resorted to in explanation of observed phenomena only when these cannot be derived in any way from the operation of known causes—यदि अदृष्टमन्तरेण दृष्टं न सिद्ध्यति काममदृष्टं कल्यताम् अन्यथा अपितु तदुपपत्तौ किं तदुपकल्पनेन । दृष्टसिद्धयेहि अदृष्टं कल्प्यते नतु दृष्टविघाताय । न्यायमञ्जरी—Âhnika 1.

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Similarly, Jayanta notes that, when anything is put down as natural (स्वाभाविक), we may mean either that it has no cause or no uniform cause, or no known cause. Of these the first two alternatives must always be dismissed ; and “natural” can only mean something of which the cause has not yet been ascertained (स्वाभाविकं नाम किमुच्यते किमहेतुकं अविज्ञातहेतुकं अनियतहेतुकं वा । न तावदहेतुकं कार्यं सम्भवति ........ नापि अनियतहेतुकं कार्यं किञ्चिदस्ति – न्यायमञ्जरी – चार्वाकमतनिरास ।)

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This sound interpretation of Adṛiṣṭa was afterwards obscured. In modern writers of the Nyâya-Vaiśeṣika school, physical and mechanical ideas have suffered a set-back, and even the formation of the hail-stone is ascribed to the operation of moral causes (धर्माधर्म).

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II. We come now to motions produced by contact (संयोग). Such motions may be classed as follows, according to the nature of the contact originating them :—

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(1) Motion due to direct contact with a body exercising continued pressure (नोदन), *e.g.* the motion of an object pushed or pulled by the hand, the motion of the mud under heavy stones, the motion of the arrow due to the pressure exercised by the bow-string, the motion of the bow-string due to the pressure of the elastic bow as it recovers its original shape, the motion of clouds, of volumes of dust, of balloons, sailing vessels and other vehicles under the impelling force (pressure, नोदन, प्रेरण) of the wind, etc. वायुर्मेघादिप्रेरणधारणादिसमर्थः Praśastapâda, वायुनिरूपण-मेघादोत्यादिपदेन यानपोतादिपरिग्रहस्तेषामपि वायुना प्रेर्य्यमाणत्वात् । Śrîdhara मेघादीति चादिग्रहणात् वेहायसानां विमानादीनां (balloons in the sky) भौमादीनां च पानपात्रपांशुपटलादीनां जलानलयोश्च परिग्रहः (Udayana, Kiraṇâvalî, वायुनिरूपणम् ).

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*N. B.*—Udayana makes a similar reference to balloons filled with gas or smoke (धूमापूरितचर्म्मपुटकं) in discussing the opinion that air has weight (Kiraṇâvalî, वायुनिरूपणम्). These passages show that balloons were known in Udayana’s time (970 a.d.—*vide* उदयन, Lakṣaṇâvalî).

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(2) Motion due to direct contact for an instant with a body that strikes and produces an impact (अभिघात), *e.g.* in the cases of a stone falling against a hard object (पाषाणादिषु निष्ठुरेवस्तुनि अभिपतितेषु—Śrîdhara), the potter’s rod striking the wheel, the mortar struck against the pestle. Instantaneous disjunction is necessary to impact. If there is continued contact, the result is pressure (नोदन). In some cases there may be disjunction (*i.e.* a rebound) after continued pressure (यत्र अभिघातकं द्रव्यं भूमदेशं अभिहत्य किञ्चिदधो नोत्वा उत्पतति—श्रीधर—न्यायकन्दली).

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(3) Motion due to direct contact with an elastic body which exercises a moving force by means of its elasticity (स्थितिस्थापकत्व) in the act of restitution of the original form (यथास्थितं स्थापयति), *e.g.* the motion of the bow-string due to the force exercised by the piece of bamboo (the bent bow). This force of restitution in an elastic body is a kind of *sanskâra*, *i.e.* persistent tendency (धनुःशाखाशृङ्गदन्तास्थिसूत्रवस्त्रादिषु भुग्नसंवर्त्तितेषु स्थितिस्थापकत्वकार्य्यं संलक्ष्यते—प्रशस्तपादभाष्य, bows, twigs, tooth-bones, horn, thread, cloth, etc., are noted as elastic).

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(4) Motion due to contact with a body which is itself in contact with another which possesses Vega (impressed motion or momentum) (वेगवद्द्रव्यसंयुक्तसंयोग). This is the fact of the transmission of pressure or moving force, and the consequent production or communication of motion, as, for example, in the pulling of an object by means of a string, the pushing of the potter's wheel by the potter's rod, etc.

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