THE DIGIT OR THUMB MEASURE
Systems for measuring length have been around since the earliest periods of human civilization. For instance, during the course of the twentieth century, the meter was adopted as the base unit of length in the International System, and by a convention adopted in 1983, the meter is now defined in terms of the speed of light.
More specifically, it is defined as the distance that light will travel during
second. In ancient times, there was also a widely accepted system of length measure that was shared by the Vedic, Egyptian, Hebrew, Greek, and Roman cultures—but this ancient base unit of length was defined in terms of the human body, rather than the speed of light. This meant that it represented literally a self-referral unit of measure. The digit came to be named from a Latin term that means “finger,” yet this unit did not come from the Roman culture. In the Vedic culture, the digit was denoted by the Sanskrit terms angula (finger) and angushta (thumb).
The digit corresponds to the width of the human thumb, which is approximately 2 centimeters. Because the width of the thumb can vary from one person to the next, however, the ancient system was approximate; the base unit varied slightly from one culture to the next. In fact, memory of this system has been preserved in colloquial language: A system of approximate evaluation is commonly referred to as a “rule of thumb.”
To simplify calculations and measurements, the ancients also used two other important units of measure called the cubit and half cubit, both of which can be expressed in terms of a number of digits: A standard cubit is equal to twenty-four digits and a standard half cubit is equal to twelve digits. Interestingly, the word cubit, meaning “elbow,” is also of Latin origin.
A standard cubit is equal to approximately the distance from the crook of the elbow to the tip of the middle finger. The standard half cubit is equal to approximately the distance from the base of the wrist to the tip of the middle finger. In the Vedic tradition, the cubit was called the aratni (elbow) and the half cubit was called the vitasti (hand span).These units were also important in the Hebrew culture. For example, the Bible tells us that the dimensions of the Ark of the Covenant and King Solomon’s Temple were measured carefully using an integral number of cubits or half cubits, and hence an integral number of Hebrew digits. Similarly, Egyptologists have shown that the base of the Great Pyramid was measured carefully using an integral number of Egyptian cubits, and hence an integral number of Egyptian digits.
In spite of the approximate nature of the system, each ancient culture developed its own standards. In the Vedic culture, the thumb of the king determined the standard digit—so that the king became the ruler of his kingdom, both literally and figuratively. There are indications that the Egyptians also employed this practice—though this standard digit was not always used. For example, in Vedic rituals designed to propitiate the gods, the person who sponsored the ritual and the one for whom the ritual was being performed, the yajamana, was deemed the ruler and contributed the thumb measure. In such cases, this measure was used to determine the dimensions of the sacrificial ground (vedi), the sacred fire altar (agni), the fire bricks (ishtakas), and even the utensils used to make the offerings. In every case, these were measured carefully according to the digit of the yajamana, and in this way, the ritual became attuned to that particular person.
Yet why did all of these ancient cultures choose the thumb width as their base unit of measure? Equally important, why did the ancients take such care to measure out the dimensions of their sacred constructions using an integral number of digits?