Page:Vitruvius the Ten Books on Architecture.djvu/104

74 have said that the perfect number is six, because this number is composed of integral parts which are suited numerically to their method of reckoning: thus, one is one sixth; two is one third; three is one half; four is two thirds, or as they call it; five is five sixths, called ; and six is the perfect num­ber. As the number goes on growing larger, the addition of a unit above six is the ; eight, formed by the addition of a third part of six, is the integer and a third, called ; the addition of one half makes nine, the integer and a half, termed ; the addition of two thirds, making the number ten, is the integer and two thirds, which they call ; in the number eleven, where five are added, we have the five sixths, called ; finally, twelve, being composed of the two simple integers, is called.

7. And further, as the foot is one sixth of a man's height, the height of the body as expressed in number of feet being limited to six, they held that this was the perfect number, and observed that the cubit consisted of six palms or of twenty-four fingers. This principle seems to have been followed by the states of Greece. As the cubit consisted of six palms, they made the drachma, which they used as their unit, consist in the same way of six bronze coins, like our asses, which they call obols; and, to correspond to the fin­gers, divided the drachma into twenty-four quarter-obols, which some call dichalca others trichalca.

8. But our countrymen at first fixed upon the ancient number and made ten bronze pieces go to the denarius, and this is the origin of the name which is applied to the denarius to this day. And the fourth part of it, consisting of two asses and half of a third, they called "sesterce." But later, observing that six and ten were both of them perfect numbers, they combined the two, and thus made the most perfect number, sixteen. They found their authority for this in the foot. For if we take two palms from the cubit, there remains the foot of four palms; but the palm contains four fingers. Hence the foot contains sixteen fingers, and the denarius the same number of bronze asses.