Sanskrit prosody or Chandas refers to one of the six Vedanga, or limbs of Vedic studies. It is also an important part of the mantra – sitting in the mouth. It is the poetic metre and verse as well as its study, the latter becomes the vedanga while the former is a mantra-part. This field of study was central to the composition of the Vedas, the scriptural canons of Vedic texts.
The Chandas, as developed by the Vedic schools, included both linear and non-linear systems. The system was organized around seven major metres and each had its own rhythm, movements and aesthetics wherein a non-linear structure (aperiodicity) was mapped into a four verse polymorphic linear sequence. Sanskrit metres include those based on a fixed number of syllables per verse, and those based on fixed number of morae per verse.
Chandas (छंदः), the study of Vedic meter, is one of the six Vedāñga (limb of the Veda). When the celestial Ganges descends on earth, it is held in the matted locks of Lord Śiva and flows down from the Gangotri glacier at a rapid pace. By the time it reaches the destination, the Bay of Bengal delta, its speed is very much reduced and it meanders along the way. The rhythm of the flow changes with time. This rhythm is called chandas. Mantra and stotra as well as all vedic hymns are received in certain chandas. Chandas is the specific rhythm with which the sound flows. None of the ancient works dealing exclusively with chandas have survived. Some of the surviving works are the Chandas-Śāstra and we have good sources in the Agni Purāṇa, Bhāratīya Nāṭya Śāstra (Ch.15), and Bṛhat Saṁhitā (Ch.104). We start learning Chandas from the teachings of Śrī Acyutānanda.
In order to study the quality of the sound wave form the ancients employed various techniques. One of them was the concept of पद (pada) meaning foot. The basic pada consists of 4 syllables. Human beings have two feet (dvi-pada) and the root meter for their movement would be defined by 2×4=8 syllables. This is called a पाद (pāda) or step and is referred to as gāyatrī-pāda. Śrī Acyutānanda explains this as ‘स-स-ब-द प-र-र-ज’ (sa-sa-ba-da pa-ra-ra-ja).
Using the pada (4 syllable foot) we can explain the root of some of the chandas – dvipadā virāj (20), gāyatrī (24), uṣṇih (28), anuṣṭubh (32), bṛhatī (36), pañkti (40), triṣṭubh (44), and jagatī (48). However, all of these are really not multiples of the pāda (8 syllables).
Gāyatrī is 24 syllables = 3×8 implying that three steps of the pāda (8) are used to reach the goal. This is called त्रिकोण (trikoṇa) or simply कोण (koṇa) or the harmonic trine which is so beneficial for all beings. Each of these steps is called bhū-bhuva-svaḥ referring to the three steps taken to cover the three loka by Śrī Vāmana (avatāra).
Anuṣṭubh is 32 syllables = 4×8 syllables implying that four steps of the pāda (8) are used to reach the goal. This is called केन्द्र (kendra) or the protective quadrant which upholds the being. Anuṣṭubh meter is also called श्लोक (śloka). Maharṣi Vālmīki accidentally discovered the śloka when he was subject to great sorrow at the sight of the death of a bird. The word śloka is derived from śoka (sorrow). Vālmīki wrote the Ramayana and among the avatāra of Viṣṇu, the one subject to the highest sorrow was Śrī Rama. In jyotiṣa we use this principle of malefic-planets in kendra cause great distress and sorrow which is based on the anuṣṭubh chandas.
Once when Vālmīki walked along the Tāmasa river, he heard the sweet chirping of two Krauncha birds. Vālmīki moved closer and found them to be a couple in frolic and mating. The two birds were so engrossed that they did not notice the sage who was so close. Suddenly one of them cried out and fell to the ground as blood oozed out of its chest. The male bird has been killed by a hunter’s arrow.
The sage was deeply saddened by this terrible scene and in anger turned to the hunter and cursed him spontaneously in perfect anuṣṭubh meter. That was the first śloka (1.2.15) ever composed in anuṣṭubh chandas and also the first composed śloka of the Ramayana (although not the opening śloka).
मा निषाद प्रतिश्थाम्त्व। मगमह् शाश्वतीह् समाह्।
यत् क्रौन्च मिथुनात् एक। मवधीह् काम मोहितम्॥
mā niṣāda pratiśthāmtva | magamah śāśvatīh samāh |
yat kraunca mithunāt eka | mavadhīh kāma mohitam || 1-2-15
Translation and Meaning: C. Sri Vidya Rajagopalan
Thereafter, the sage was perplexed as to why such a meter, so perfect in grammar and rich in poetical eloquence, had occurred to him at such a time. Lord Brahma, the presiding deity of the Vedas appeared and ordained him to author the Ramayana. Later in the Bhagavataṁ, we find Vedavyāsa referring to Lord Rama with the prayer – “om namo bhagavate uttama-ślokāya”
The first śloka of the Ramayana is –
तपह् स्वाध्याय निरताम् तपस्वी वाग्विदाम् वरम्।
नारदम् परिपप्रच्च वाल्मीकिह् मुनि पुम्गवम्॥ १-१-१
tapah svādhyāya niratām tapasvī vāgvidām varam |
nāradam paripapracca vālmīkih muni pumgavam || 1-1-1
In this manner one can understand the difference between some of the chandas which are based on the 4-syllable pada.
Normally most chandas are defined by the number of pāda (steps) and the pāda can have more than eight syllables. Whereas the Gāyatrī and Anuṣṭubh are based on 8-syllable pāda, many others are not. Virāj is based on 10-syllable pāda while triṣṭubh and jagatī are based on 11 and 12 syllable pāda.
Virāj chandas = 10 × 4 = 40 syllables
Triṣṭubh chandas = 11 × 4 = 44 syllables
Jagatī chandas = 12 × 4 = 48 syllables
Although the uṣṇih chandas is 28 syllables and we would think of it as having 4 pāda of 7-syllable each, it is not so. The uṣṇih chandas is tri-pāda like the gāyatrī chandas and is more by 1 pada (4 syllables) and is composed of 8 + 8 + 12 = 28 syllables. The kākubh chandas is similar to uṣṇih in syllables but has an elongated second pāda instead of third and is written as 8 + 12 + 8 = 28 syllables. This brings in another level of complexity but does clearly define a different rhythm. We now realise that the pāda can not only have different lengths other than the standard 8 syllables but can also be of varying length. In addition, the number of pāda defining the complete chandas need not be limited.
Of the sixteen vowels in Sanskrit, technically eight are supposed to be short (laghu) and eight syllables are to be guru (long). However, the anusvara and visarga are treated as guru (long) bringing about a little imbalance.
Now we are getting into too many things. The point is that Chandas is in the mouth of the user and is an important limb of the mantra. Please note that so far we have only discussed one aspect of the sound wave which is the period of the sound which we call pāda and have not made any mention of the amplitude.
 Numenius Arquata i.e. Curlew
 Meaning 1:
ama nisaada= oh, ill fated, hunter; tvam= you; yat= by which reason; krauncha mithunaat = of krouncha, couple; ekam= one; kaama mohitam= lust, indulged in; a-vadhiih= you killed; [tat= by that reason]; shaashvatiih= ever lasting; samaah= ages to come; pratisthaam tu= reputation, but; maa gamah= don’t, get.
“Oh! Ill-fated Hunter, by which reason you have killed one male bird of the couple, when it is in its lustful passion, thereby you will get an ever-lasting reputation for ages to come…” [1-2-15]
maa= Goddess Lakshmi; nishaada= Oh! Vishnu [ for Goddess Lakshmi resides in the heart of Vishnu – nishadiiti asmin iti niShaada ]; yat = by which act; krounca midhunaat = the couple of demons, namely Ravana and Mandodari; kaama mohitam= that impassioned one and stole Seetha; ekam= that one, Ravana; avadhii= you killed; by that act of yours; shashvatiisamaa= everlasting for ages; pratishtaam= divine sanctity; tvam agama= you, get.
“Oh, the abode of Goddess Lakshmi, namely oh, Vishnu, by which act of your killing one male demon named Ravana, who in his passion abducted Seetha, and thus you eradicated the vice from the earth, for that you get an everlasting divine sanctity, as Rama, for ages to come.”
The verse included the meaning of whole of the epic, Ramayana.
(i) maa nisaada= Goddess Lakshmi and Vishnu. Their marriage in their incarnations as Rama and Seetha, and Ramayana depicts this in Bala Kanda.
(ii) pratistaam tvam agama= renown, you get, by following your father’s orders you have repaired to forests, without any political upheaval, thus get an everlasting renown as an obliging son Ayodhya Kanda.
(iii) shashavatii samaa= by dwelling in forest and eradicating demons and helping the saints and sages thus, you achieve an everlasting praise Aranaya Kanda.
(iv) krounchayoh= from the [atrocious] couple; k– krunca gati kauTilyaa alpii bhaavayoH; the atrocious Vali, and Tara couple; ekam kaama mohitam = one, passion, filled, i.e., Vali; avadhii= you killed, you killed Vali Kishkindha Kanda.
(v) krouncha mithunaat= from the couple of lovely passionate birds here Rama and Seetha; niSaada that ruffian Ravana, kaama mohitam lustfully, ekam one [i.e., Seetha]; avadhii = almost killed, i.e., her residing in Lanka is as good as death Sundara Kanda.
(vi) krouncha mithunaat = from the atrocious, couple Ravana and Mandodari; ekam avadhii one Ravana, you killed Yuddha Kanda.
(vii) kaama mohitam= by desire, fascinated [ kama also means a longing, desire, let alone lusting]; Seetha is fascinated by her desire to see sage’s wives in uttara Ramayana and thus she is sent to forests through Lakshmana. Hence seventh canto, uttara Ramayana is also suggested.