The Positive Sciences of the Ancient Hindus c9.t1.37

c9.t1.37

The cerebro-spinal axis and the heart: their respective relations to the conscious life.—Vijnânabhikshu, in the passage just quoted, identifies the *Manovahâ Nâḍî* (vehicle of consciousness, चित्तस्थान) with the cerebro-spinal axis and its ramifications, and compares the figure to an inverted gourd with a thousand-branched stem hanging down. The *Suṣumna*, the central passage of the spinal cord, is the stem of this gourd (or a single branch). The writers on the Yoga (including the authors of the various Tantric systems) use the term somewhat differently. On this view, the *Manovahâ Nâḍî* is the channel of the communication of the *Jîva* (soul) with the *Manaschakra* (sensorium) at the base of the brain. It has been stated that the sensory currents are brought to the sensory ganglia along afferent nerves of the special senses. But this is not sufficient for them to rise to the level of discriminative consciousness (सविकल्पकज्ञानम्). A communication must now be established between the *Jîva* (in the *Sahasrâra Chakra*, upper cerebrum) and the sensory currents received at the sensorium, and this is done by means of the *Manovahâ Nâḍî*. When sensations are centrally initiated, as in dreams and hallucinations, a special *Nâḍî* (*Svapnavahâ Nâḍî*), which appears to be only a branch of the *Manovahâ Nâḍî*, serves as the channel of communication from the *Jîva* (soul) to the sensorium. In the same way, the *Âjnâvahâ Nâḍî* brings down the messages of the soul from the *Sahasrâra* (upper cerebrum) to the *Âjnâ Chakra* (motor tract at the base of the brain), messages which are thence carried farther down, along efferent nerves, to various parts of the periphery. I may add that the special sensory nerves, together with the *Manovahâ Nâḍî*, are sometimes generally termed *Jnânavahâ Nâḍî*, *lit.* channel of presentative knowledge. There is no difficulty so far. The *Manovahâ Nâdî* and the *Âjnâvahâ Nâdî* connect the sensori-motor tract at the base of the brain (*Mânaschakra* and *Âjnâchakra*) with the highest (and special) seat of the soul (*Jîva*) in the upper cerebrum (*Sahasrâra*), the one being the channel for carrying up the sensory, and the other for bringing down the motor messages. But efforts of the will (*Âjnâ*, *Prayatna*) are conscious presentations, and the *Manovahâ Nâdî* must therefore co-operate with the *Âjnâvahâ* in producing the consciousness of effort. Indeed, attention, the characteristic function of *Manas*, by which it raises sense-presentations to the level of discriminative consciousness, implies effort (*Prayatna*) on the part of the soul (*Âtman*, *Jîva*), an effort of which we are conscious through the channel of the *Manovahâ Nâdî*. But how to explain the presentation of effort in the motor nerves? Śaṅkara Miśra, the author of the *Upaskâra* on *Kanâda's Sûtras*, argues that the *Nâdîs* (even the volitional or motor nerves) are themselves sensitive, and their affections are conveyed to the sensorium by means of the nerves of the (inner) sense of touch (which are interspersed in minute fibrillæ among them). The consciousness of effort, then, in any motor nerve, whether *Âjnâvahâ* (volitional-motor) or *Prâṇavahâ* (automatic-motor), depends on the tactile nerves (or nerves of organic sensation) mixed up with it. Thus the assimilation of food and drink by the automatic activity of the *Prâṇas* implies an (automatic) effort (जीवनयोनिप्रयत्न) accompanied by a vague organic consciousness, which is due to the fact that minute fibres of the inner touch-sense are interspersed with the machinery of the automatic nerves (the *Prâṇavahâ Nâḍîs*).