Just as colours exist in many-stepped gradations produced by the different capacities for light absorption possessed by different types of matter, so are the wavelengths of vowels shaped into tiers of light and shade by the high or low and front or back position of the tongue during the process of articulation. All Indo-European languages exhibit traces, in different degrees of clarity, that, from very early on, the speakers of the original Indo-European mother-tongue used a three-tiered system of vowel gradation to distinguish different forms of verbs, on the one hand, and different nouns derived from one root, on the other. The most faithful representation of this system is to be found in ancient Greek, where diphthongs exist in three grades of strength. The first, the e-grade, is always characterised by the vowel as first element of the diphthong, to which either an or an u is added. In the second, or o-grade, the initial vowel changes to o, while the second element or remains unchanged. The third grade is called zero grade because only the second element of the diphthong is kept, the first being replaced by zero, i.e. nothing. This results in the series of vowel gradations ei – oi – i and eu – ou – u, for example. The so called irregular verbs of English, which change their stem-vowel in the formation of the past tense and past participle, such as drive – drove – driven, take their origin from exactly the same process of gradation. The forms of the verb drive are the English reflection of the Greek gradation ei – oi – i.

Sanskrit too, has a pervasive system of vowel gradation, equally working on the basis of a distinction between three degrees of strength. Since, just as sandhi, the subject of the previous 101 article, this system is no longer productive in Hindi, its workings, originally designed to help the user of the language in associating a certain word with a certain root and therefore meaning, will often confuse the learner of modern Hindi who has no knowledge of the classical language of India. Since it is neither the wish of most Hindi students to acquire a working knowledge of Sanskrit, nor required in order reach a better understanding of commonly occurring Sanskrit forms in Hindi, this article provides a short introduction to the system of vowel gradation of Sanskrit. Readers interested in the finer details of the correspondence between the representation of the Indo-European system of vowel gradation in Greek and Sanskrit are advised to read the article Why are the vowels ए (ē) and ओ (ō) always long? before continuing to the next paragraph of the present article.

The three grades of vowel gradation of Sanskrit are called, from weak to strong, स्वर (svara), गुण (guṇa) and वृद्धि (vṛddhi). स्वर (svara) corresponds to the zero grade of Greek, e.g. the simple vowel इ (i) or उ (u). गुण (guṇa) corresponds to the e-grade of Greek, e.g. the monophthongised Indo-European diphthongs ए (e) and ओ (o). In Sanskrit the o-grade is no longer to be distinguished from the e-grade, since all diphthongs in became ए and all diphthongs in u became ओ. In order to recover something similar to the original three-tiered system of vowel gradation Sanskrit came up with a kind of super-strong grade called वृद्धि (vṛddhi), in which ए (e) is further strengthened to ऐ (ai) and ओ (o) to औ (au). This results in the two series of vowel gradations: इ – ए – ऐ and उ – ओ – औ. In Sanskrit, the vowel ऋ (ṛ) also takes part in gradation. Its three grades are: ऋ (ṛ), अर् (ar) and आर् (ār). Below are a few examples of each of the gradation series as they are found in Hindi words of Sanskrit origin.

The root विद् (vid) means to know. The noun विद्या, knowledge, is based on its zero grade, so is the word विद्वान, which can be either an adjective meaning learned or a noun meaning scholar. The name of the four most ancient Indian sacred scriptures is derived from the गुण (guṇa) grade of the same root: वेद (veda). Something that pertains to the Vedas is called वैदिक (vaidik) and based on the वृद्धि (vṛddhi) of the root विद् (vid). Note that the common suffix -इक (-ika) always causes the root to appear in its strongest grade.

The root भुज् (bhuj) means to eat or enjoy. Its past passive participle, which uses the suffix -त (-ta) and always has causes the zero grade of the root, is भुक्त (bhukta), meaning eaten. Using another suffix the noun भुक्ति (bhukti), enjoyment, is formed, equally on the zero grade of the root. In the word for meal the same root appears in the गुण (guṇa) grade: भोजन (bhojana). A word in which the root भुज् (bhuj) appears in the strongest grade is not to be found in Hindi, but in the adjective भौम (bhauma), pertaining to the earth, there is an example of the वृद्धि (vṛddhi) of the vowel ऊ (ū) of the noun भूमि (bhūmi), meaning the earth.

The most common root containing the vowel ऋ (ṛ) is without doubt कृ (kṛ), which means to make. In the past passive participle the root appears again in the zero degree: कृत (kṛta), done, performed or made. The adverb कृते (kṛte), on behalf of, equally uses the weakest form of the root. In the well known noun कर्म (karma), deed or action, the same root appears in the गुण (guṇa) grade. The वृद्धि (vṛddhi) grade is found in the common noun कारण (kāraṇa), meaning reason or cause.


Silvio Zinsstag,

teacher for ancient languages