वृद्धो यूना तल्-लक्षणश् चेद्-एव विशेषः

The word sesha of the previous sutra is understood here. The word \yuna\ in the text is in the instrumental case. The yuvan word is dropped when read along with a Vriddha word. The word Vriddha means gotra: the old acharyas (grammarians) used the word Vriddha for gotra. The vriddha (or in other words, the gotra) word designates a person between whom and original head of the family a son (or a word formed by an apatya affix) intervenes. In using together two words, one formed by a gotra affix and the other by a yuvan affix, the Vriddha is retained, where the difference between those words is in their affixes only. These two words, gotra and yuvan, are defined in sutras 4.1.162 and 4.1.163. (अपत्यं पौत्रप्रभृति गोत्रम् ॥ जीवति तु वंश्ये युवा) ॥ Roughly speaking a gotra word is formed from the original noun which is the name of the head of the family when a son of such person is living; and a vriddha word represents thus a grandson, or lower than that, but not a son; while a yuvan word is derived from such last mentioned gotra word by another affix and thus represents persons lower than grandsons.

The word 'tad' in the sutra refers to the gotra and yuvan affixes. The word lakshana 'sign' in the sutra is synonymous with 'cause' or 'occasion'; meaning the specific difference is caused or occasioned by the gotra and yuvan affixes. The word चेत् in the sutra means 'if.' The word एव 'only' is used to exclude others. The word विशेषः in the sutra means the 'dissimilarity of form.'

Thus गार्ग्यः + गार्ग्यायणः = गार्ग्यौ. Here the first word denotes a clan called Gargya (the offspring or grandsons of Garga formed by the affix यञ् (IV. I. 105) \\[1\\] the second word denotes a younger branch of the same, and is formed by the Taddhita affix denoting a secondary derivative \\[2\\]. In this then, the first or \Vriddha\ remains; the second or the yuvan is dropped; and the form \Gargyau\ means both the old and the new clan. Similarly वात्स्यः + वात्स्यायनः = वात्स्यौ ॥

This Ekasesha is to be done only in those cases, where the two words have the same radical form, the only difference between them being in their derivative formation.

The words must differ only by their affixes, but their radical element must be the same. The rule therefore does not apply to:- गार्ग्यः (a Vriddha word + वात्स्यायनः (a yuvan word) = गार्ग्यवात्स्यायनौ ॥

This rule of ekasesha does not apply if one of the words be not a Vriddha word. Thus गर्गः + गार्ग्यायणः = गर्गगार्ग्यायणौ ॥

Similarly vice versa गार्ग्यः + गर्गः = गार्ग्यगर्गौ । Here the one word is Vriddha, but the other is not yuvan.

The word \only\ is used in the sutra in an exclusive sense, the force being, that two words may stand in the relation of Vriddha and yuvan, their radical element, i.e. form may be the same; but if the secondary word has another sense over and above the sense of a yuvan affix, this rule is not applicable. Thus rule 4.1.148 \\[3\\] says a \Vriddha word may optionally take the affix ठक् to form a yuvan word and to indicate contempt and born in the country of Sauvira.\ Thus भागवित्तिः + भागवित्तिकः = भागवित्तिभागवित्तिकौ. Here the second word, though a yuvan word, connotes the additional sense of contempt and degradation. The affix ठक् is not merely a yuvan affix but conveys the other sense also, the pure yuvan word being भागवित्तायनः.

N. B.- The system of domestic economy among the ancient Aryas was considerably difterent from the prevalent one. The surnames or the gotras represented the patriarchal system. Three forms of surnames are constantly met with in ancient literature. The first was most important: it was the patronymic by which the lord of the united family, the patriarch, was known. For example, Garga or Gargacharya was the recognised head of all the Gargas who may be a hundred. His eldest son and heir was called Gargi. This is the first form of the patronymic (apatya). The grandsons or sons of Gargi were named Gargyas (Vriddham or Gotra). On the decease of the old patriarch, Gargi began to be called Garga; and the eldest of the grandsons was called Gargi; and those great-grandsons who belonged to the family, and were designated Gargayanas (yuvan) were now called Gargyas.

## Footnotes
- [1] - गर्गादिभ्यो यञ् ॥
- [2] - यञिञोश्च ॥
- [3] — वृद्धाट्ठक्सौवीरेषु बहुलम् ॥,