But we may once more turn aside from the physical to the intellectual aspect of available evidence, and find confirmation of a like kind in one of the earliest definite manifestations of cultured reason. Few tests of relative stages of civilisation are more trustworthy than that of the definite conception of high numbers. The prevalence of a decimal system of numerals among widely severed nations, alike in ancient and modern times, has been universally ascribed to the simple process of counting with the aid of the fingers. Mr. Francis Galton, in his Narrative of an Exploration in Tropical Africa, when describing the efforts of the Damaras at computation, states that the mental effort fails them beyond three. “When they wish to express four, they take to their fingers, which are to them as formidable instruments of calculation as a sliding rule is to an English schoolboy. They puzzle very much after five, because no spare hand remains to grasp and secure the fingers that are required for units.” Turning to the line of evidence which this primitive method of computation suggests, some striking analogies reveal a recognition of ideas common to the savage and to the cultivated Greek and Roman. Donaldson, in his New Cratylus, in seeking to trace the first ten numerals to their primitive roots in Sanskrit, Zend, Greek, and Latin, derives seven of them from the three primitive prenominal elements. But five, nine, and ten are referred by him directly to the same infantile source of decimal notation, suggested by the ten fingers, as has been recognised in similar operation among the Hawaiians, and the Maoris of New Zealand. “One would fancy, indeed, without any particular investigation of the subject, that the number five would have some connection with the word signifying ‘a hand,’ and the number ten with a word denoting the ‘right hand’; for in counting with our fingers we begin with the little finger of the left hand.” Hence the familiar idea, as expressed in its simplest form, where Hesiod (Op. 740) calls the hand πέντοζον, the five-branch; and hence also πεμπάζω, primarily to count on five fingers.
Bopp, adopting the same idea, considers the Sanskrit pan’-cha as formed of the copulative conjunction added to the neuter form of pa, one, and so signifying “and one.” Benary explains it as an abbreviation of pân’-i-cha, “and the hand”—the conjunction being equally recognisable in pan’-cha, πέν-τε, and quinque. This, they assume, expressed the idea that the enumerator then began to count with the other hand; but Donaldson ingeniously suggests the simpler meaning, that after counting four the whole hand was opened and held up. To reckon by the hand was, accordingly, to make a rough computation, as in the Wasps of Aristophanes, where Bdelycleon bids his father, the dicast, “first of all calculate roughly, not by pebbles, but ἀπὸ χειρός, with the hand.”
The relation of δεξιά to δέκ-α and dextra, δέκ-α, decem, δεκ-σιός, decster, illustrates the same idea. Grimm, indeed, says, “In counting with the fingers, one naturally begins with the left hand, and so goes on to the right. This may explain why, in different languages, the words for the left refer to the root of five, those for the right to the root of ten.” Hence also the derivation of finger, through the Gothic and Old High German, from the stem for “five” and “left”; while the Greek and Latin, δάκτυλος and digitus, are directly traceable to δέκα and decem. The connection between ἀριστερά and sinistra is also traced with little difficulty: the sibilant of the latter being ascribed to an initial digamma, assumed in the archaic form of the parent vocabulary. Nor is the relationship of δεξιά with digitus a far-fetched one. As the antique custom was to hand the wine from right to left, so it may be presumed that the ancients commenced counting with the left hand, in the use of that primitive abacus, finishing with the dexter or right hand at the tenth digit, and so completing the decimal numeration.
The inferior relation of the left to the right hand was also indicated in the use of the former for lower, and the latter for higher numbers beyond ten. In reckoning with their fingers, both Greeks and Romans counted on the left hand as far as a hundred, then on the right hand to two hundred, and so on alternately: the even numbers being always reckoned on the right hand. The poet Juvenal refers to this in his tenth Satire, where, in dwelling on the attributes of age, he speaks of the centenarian, “who counts his years on his right hand”—
Felix nimirum, qui tot per secula mortem
Distulit, atque suos jam dextra computat annos,
Quique novum toties mustum bibit.
A curious allusion, by Tacitus, in the first book of his History, serves to show that the German barbarians beyond the Alps no less clearly recognised the significance of the right hand as that which was preferred, and accepted as the more honourable member. The Lingones, a Belgian tribe, had sent presents to the legions, as he narrates: and in accordance with ancient usage gave as the symbolical emblem of friendship two right hands clasped together. “Miserat civitas Lingonum vetere instituto dona legionibus, dextras, hospitii insigne.” The dextræ are represented on a silver quinarius of Julius Cæsar, thus described in Ackerman’s Catalogue of rare and unedited Roman Coins, “PAX. S. C. Female head. Rev. L. AEMILIVS. BVCA. IIII. VIR. Two hands joined.”[6]
[6] Ackerman, i. 106.
Other evidence of a different kind confirms the recognition and preferential use of the right hand among our Teutonic ancestors from the remotest period. Dr. Richard Lepsius, in following out an ingenious analysis of the primitive names for the numerals, and the sources of their origin, traces from the common Sanskrit root daça, Greek δέκα, through the Gothic taihun, the hunda, as in tva hunda, two hundred. He next points out the resemblance between the Gothic hunda and handus, i.e. “the hand,” showing that this is no accidental agreement, but that the words are etymologically one and the same. The A.S. hund, a hundred, originally meant only “ten,” and was prefixed to numerals above twenty, as hund-eahtatig, eighty, hund-teontig, a hundred, etc.