The study of the early history of coined money is a most curious one. Rude peoples pass from barter to the use of metallic currency; and the most general article of wealth is taken as the standard to which, either as a multiple or a fraction, all other possessions are adjusted.[21] In Greece, as in Italy, the ox was the unit of value, and in Italy[22] a piece of metal was stamped with the impression of an animal (_nota pecudum_), whence it was termed _pecunia_,[23] but when and by whom such a stamp was first placed on “the bar or piece of metal it is, of course, impossible to say.” The Egyptian inscriptions, fortunately, throw some light on this subject, for as early at least as B.C. 1700, a [Egyptian **] _khetem_ is mentioned as a unit of value for metals, while “an ox” is valued as one seal. Furthermore, the word [Egyptian **] _khetem_, determined by an ox, actually occurs as a measure of value, and means a seal with the figure of an ox stamped on it, or an ox skin sealed.[24]
We have just seen that the affixing of a seal to a document gave to that document its validity and binding force, and it is now not difficult to realize that, being the real instrument of the power and authority of an office, it should have become the symbol of it. The delivery therefore of the seal or signet either by the king or by his minister, committed to the individual the authority and power to execute the rights and duties of his office. The Egyptian monarch himself was invested at his Coronation[25] with the Royal Signet,[26] upon which his name and titles were engraved; this was as important a part of the insignia of royalty as his sceptre or his crown. In an early text (_circa_ 2500 B.C.) it is said that “Mer-en-Ra maketh his appearance as king, he hath taken possession of his signet (_sah_) and of his throne.”[27] The word for signet is here [Egyptian **] _Sah_ (variants [Egyptian **] and [Egyptian **] _Sah_, note the necklace and cylinder seal as determinative), and the signet was repeatedly used in ancient Egypt to denote a man of noble rank, one who was allowed to carry a signet with the royal name engraven upon it. Osiris is named _Sahu_, “seal bearer” of the gods whom he has called into existence, and a hymn[28] calls him the glorious _Sahu_ among the _sahus_. The Prince Khnemhetep (2000 B.C.), at Beni Hasan, says of himself that he was distinguished above all the king’s nobles _(sahu)_; that is to say, the order of men bearing the signet or sign of investiture. A mummified person is also called _Sahu_, in virtue of investiture.[29]