Rex, which is attested only in Italic, Celtic, and Indic—that is, at the western and eastern extremities of the Indo-European world—belongs to a very ancient group of terms relating to religion and law.

The connection of Lat. rego with Gr. orégō ‘extend in a straight line’ (the o– being phonologically explicable), the examination of the old uses of reg– in Latin (e.g. in regere fines, e regione, rectus, rex sacrorum) suggests that the rex, properly more of a priest than a king in the modern sense, was the man who had authority to trace out the sites of towns and to determine the rules of law.

There are certain notions which we can attribute to the Indo-Europeans only by indirect means because while they refer to social realities, they are not manifested by facts of vocabulary common to the whole group of languages. Such is the concept of society. In western Indo-European it is designated by a common term. But this seems to be lacking in the other groups. In fact, it is expressed in a different way. It may be recognized under the name of kingdom: the limits of society coincide with the extent of a given power, which is the power of the king. This poses the problem of the words for “king,” a problem which involves both the study of society and the divisions which characterize it and the study of the hierarchies which, within society, define its groupings.

When we approach this notion of “king” in its lexical expression, we are struck by the fact that the word represented by rex appears only at the two extremities of the Indo-European world and is missing in the central part. We find on the one side rex in Latin, while Celtic is represented by Irl. ri and Gaulish –rix; at the other extremity we have Sanskrit rāj-(an). There is nothing in between, not in another Italic language, nor in Germanic, Baltic, Slavic or Greek, or even in Hittite. This correlation is extremely important for appreciating the distribution of the common vocabulary among the different languages. We must regard the case of rex as an instance—probably the most notable—of a wider phenomenon studied by J. Vendryes: [1] that of the survival of terms relating to religion and law at the two extremities of the Indo-European world, in the Indo-Iranian and Italo-Celtic societies.

This fact is bound up with the very structure of the societies in question. It is not a simple accident of history if in the “intermediate” languages, we find no trace of this word for “king.” In the case of both Indo-Iranian and Italo-Celtic we are concerned with societies of the same archaic structure, of an extremely conservative nature, where institutions and their vocabulary persisted long after they had been abolished elsewhere. The essential fact which explains these survivals that are common to the Indo-Iranian and Italo-Celtic societies is the existence of powerful colleges of priests who were the repositories of sacred traditions which they maintained with a formalist rigor.

It will suffice to cite, among the Romans, the colleges of the Arval Brothers, among the Umbrians the fratres Atiedii of Iguvium, among the Celts, the Druids, and in the Orient priestly corporations like the Brahmans or the Atharvans of India, the āθravans or the “Magi” in Iran.

It is thanks to the persistence of these institutions that a large part of the religious ideas of the Indo-Europeans have survived and are known to us, inasmuch as they were regulated by complex rituals which remain our best sources of information.

However we should guard against believing that it was only because of the archaism of society that these facts have been preserved in these cases and not elsewhere. The changes made in the very structure of institutions have brought it about that the specific notion of rex was unknown to other peoples. There are certainly words both in Greek and in Germanic which may be translated as “king.” But the Greek basileús has nothing in common with the rāj, and the numerous words in Greek which mean “king” or rather “chief” go to show that the institution had been remodeled.

The nominal stem *rēg– of the Latin rēx, rēgis is exactly that of the Irish ri and the Gaulish –rix, which is found as a component of compound personal names such as Dumno–rix, Ver–cingeto–rix. The form presupposed by Sanskrit rāj– is exactly the same; it goes back to an ancient *rēg-. This root is probably also found in the royal Thracian name Rhēsos.

What is the meaning of this term? What is the semantic basis of the concept? In Latin rex produced a whole family of words, among which is the derived verb rego, regere, the derived neuter noun reg–no–m, the feminine rēgīna, with a very characteristic formation seen also in Skt. rājñī ‘queen’, both formations making use of a suffix –n-to mark the “motion,” that is, the feminization of an ancient masculine. Regio and rectus form a group of their own. There is no longer any connection in Latin itself between rex and rectus. However, morphological relationships which are clear and of a well known type attach regio and rectus to the root of rex. Both these derivatives have a correspondent elsewhere. Thus Latin rectus is paralleled by Gothic raihts (Germ. recht); yet Germanic does not exhibit the nominal term *rēg-.

The first question we must pose is therefore whether other Indo-European languages have not preserved, in some vestigial way, related forms. Greek has a verb which it is tempting to connect with rego and the family of rex; but it is so different in sense that one is reluctant to do so in a formal way. This is the verb orégō (ὀρέγω), which is translated as “stretch, stretch out.” It is difficult to see how this connection can be established, and so it is usually put forward with some doubt and merely as a possibility. If we were able either to refute this relationship or to make it acceptable we should have made an important contribution towards the definition of the notion of “royalty.”

The problem is in the first place a phonetic one: since the correspondence between the roots *reg– of Latin rego and reg– of Gr. o–rég–ō is self-evident, can we explain the initial o– of the Greek word? This is not an insignificant detail. It concerns the most ancient morphology of Indo-European. In Greek we find under similar conditions, especially before r, a prothesis consisting of one of the vowels a, e, o, in a position where no initial vowel appears in the other languages. An example is eruthrós (ἐρυθρός) with a prothetic e– as compared with Latin ruber. We see in this particular instance the same phenomenon as in orégō. It will not be possible to discuss this peculiarity in detail here and we content ourselves with noting that it forms part of a general linguistic phenomenon. The languages of the world do not all necessarily possess both the liquid consonants r and l. We must not believe that it is absolutely necessary to distinguish these two liquids and we should look in vain for them in all languages. In fact languages may use either r or l or both. There is a striking contrast between Chinese which uses l but not r, and Japanese, which uses r but not l. In other cases both r and l actually are heard in the language, but they do not correspond to distinct phonemes. In French it is not permissible to confuse roi and loi (“king” and “law”), for r and l are certainly two different phonemes, each of which has its place within the phonemic system. But there exist languages of very different type which use r and l without distinction (Polynesian is a case in point), that is to say, as a liquid with a variable mode of articulation.

How does it stand with Indo-European? The common system certainly possesses two phonemes r and l, though they have different functional values: r is used more frequently and in more different ways than l. But both existed at the earliest period, although they came to be confused to a great extent in Indo-Iranian.

However it is not sufficient to establish the presence of the two liquids in Indo-European. It is known that not all the phonemes of a language appear in every conceivable position. For each phoneme certain positions are permitted while in others it is excluded. In Greek a word may end only with one of the consonants –n, –r, or –s, the sole exception being the negation ou(k). It follows that there is in each language a register of possibilities and impossibilities which characterize the use of its phonological system.

Now it is a fact that in many languages there is no initial r. In Finno-Ugrian, Basque, and other languages no word may begin with r. If a borrowed word begins with an r, it is given a preceding vowel, which puts the r in a medial position. Such is also the situation in common Indo-European : an r is not permitted in the initial position. In Hittite, for instance, there is no initial r although we find words with initial l. Similarly with Armenian: in order to accommodate borrowed words beginning with an r Armenian prefixes them with an e or, more recently, replaces the original r– by a strongly rolled r distinct from the normal r. This is also the case in Greek where a “prothetic vowel” appears before r, so that the words begin with er-, ar-, or-.

The fact must be stressed. If Greek, Armenian and Hittite have no initial r-, this is because they have continued the absence of initial r-in Indo-European. These languages have preserved the ancient state of affairs. It is by virtue of a phonetic transformation that Latin on the one hand and Indo-Iranian on the other present r at the beginning of a word. On the other hand initial l– existed in Indo-European and is preserved as such: cf. the root *leik^w– and Gr. leípō (λείπω), Lat. linquo, without prothesis. When Greek presents an initial r-, it always carries a rough breathing, i.e. ῥ (= rh-), which indicates an original *sr– or an original *wr-. Apart from this, the original initial *r– is always preceded by a prothesis.

Thus in theory there is nothing against the connection of rex with Greek orégō: the o– offers no obstacle to the equation, for it attests an original word beginning which has not been preserved in Latin. It remains to determine the sense of the Greek forms. The present orégō or orégnumi (ὀρέγνυμι) with its derivative órguia (ὄργυια) (feminine form of the substantivized perfect participle with the sense “fathom”) does not simply mean “stretch”; this is also the sense of another verb, petánnumi (πετάννυμι). But petánnumi means “spread out sideways,” while orégō, orégnumi mean “stretch out in a straight line,” or more explicitly, “to draw forward from the point where one stands in a straight line,” or “to betake oneself forwards in a straight line.” In Homer orōrékhatai (ὀρωρέχαται) describes the movement of horses which stretch themselves out at full length as they run.

This sense is also present in Latin. The important word regio did not originally mean “region” but “the point reached in a straight line.” This explains the phrase e regione ‘opposite’, that is, “at the straight point, opposite.” In the language of augury regio indicates “the point reached by a straight line traced out on the ground or in the sky,” and “the space enclosed between such straight lines drawn in different directions.”

The adjective rectus can be interpreted in a similar way: “straight as this line which one draws.” This is a concept at once concrete and moral: the “straight line” represents the norm, while the regula is “the instrument used to trace the straight line,” which fixes the “rule” (règle). Opposed to the “straight” (droit) in the moral order is what is twisted, bent. Hence “straight” (droit) is equivalent to “just,” “honest,” while its antonyms “twisted, bent” (tordu, courbé) is identified with “perfidious,” “mendacious,” etc. This set of ideas is already Indo-European. To Lat. rectus corresponds the Gothic adjective raihts, which translates Gr. euthús ‘straight’; further the Old Persian rāsta, which qualifies the noun “the way” in this injunction: “Do not desert the straight way.”

In order to understand the formation of rex and the verb regere we must start with this notion, which was wholly material to begin with but was susceptible to development in a moral sense. This dual notion is present in the important expression regere fines, a religious act which was a preliminary to building. Regere fines means literally “trace out the limits by straight lines.” This is the operation carried out by the high priest before a temple or a town is built, and it consists in the delimitation on a given terrain of a sacred plot of ground. The magical character of this operation is evident: what is involved is the delimitation of the interior and the exterior, the realm of the sacred and the realm of the profane, the national territory and foreign territory. The tracing of these limits is carried out by the person invested with the highest powers, the rex.

Thus in rex we must see not so much the “sovereign” as the one who traces out the line, the way which must be followed, which also represents what is right. The concrete idea expressed by the root *reg– was much more alive than we imagined in rex at the outset. This concept of the nature and power of the rex also agrees with the form of the word. It is an athematic form without suffix and it has the aspect of words which are used especially as the second term of compounds; e.g. –dex in iū–dex, an agent noun based on *deik-. This is supported by examples in other languages than Latin: e.g. in the compound Gaulish names containing –rix such as Dumno–rix, Ver–cingeto–rix. In Sanskrit rāj– occurs less frequently as an independent word than in composition: sam–rāj– ‘king common to all’, sva–rāj– ‘self-ruler, he who is king of himself’. In fact in Latin itself rex appears with specific determinants, notably in the ancient phrase rex sacrorum. The rex was charged with the task regere sacra, in the sense in which the expression regere fines is taken.

In this way we can give definition to the concept of the Indo-European kingship. The Indo-European rex was much more a religious than a political figure. His mission was not to command, to exercise power, but to draw up rules, to determine what was in the proper sense “right” (“straight,” droit). It follows that the rex, as thus defined, was more akin to a priest than a sovereign. It is this type of kingship which was preserved by the Celts and the Italic peoples on the one hand and the Indic on the other.

This notion was bound up with the existence of great colleges of priests whose function it was to perpetuate the observance of certain rites. It needed a long process of evolution and a radical transformation to reach the kingship of the classical type, which was founded exclusively on power, political authority becoming progressively independent of religious power, which in the end devolved on the priests.