The choice of stopping the count at four could be due to two factors. Firstly, the human hand consists of four fingers, excluding the thumb. In this context, the thumb was possibly not considered a 'finger' like the others. Secondly, a handsbreadth measurement, excluding the thumb, was a common unit in many ancient civilizations. For instance, the Greek and Egyptian ell was comprised of six handsbreadths, each with four fingers, totalling 24 fingers. Similarly, the Roman foot, or pes, was divided into four palmae, each of four digiti. This historical use of the hand as a measurement tool could explain the emphasis on the number four in early counting systems. A subsequent preference for quartets, or four-part divisions, in various classification systems may further reflect a cognitive tendency to find balance and comprehensibility in the number four. This tendency is evident in various cultural, philosophical, and scientific contexts. For example, in (Western) philosophy there are the classical elements (earth, water, air, fire); in biology, the four bases of DNA (adenine, cytosine, guanine, thymine); and in proto-psychology, the four temperaments. These examples illustrate how quartets bring structure and understanding to complex systems.