The study of the language sometimes has to face questions or issues of difficult explanation that are lost in the mists of time.
With the term "calculation" (from the Latin "calculus”, diminutive of calx,-cis = pebble, small stone; probably Greek loan χάλιξ = limestone) we refer to stones that are formed in the kidney and other organs of the body such as the gallbladder and that must be eliminated as soon as possible to avoid discomfort or bigger problems.
But "calculus, calculation, computation, counting" also refers to the arithmetic action "to calculate, to estimate", precisely because children learn to count with pebbles, piling them or handling them on the abacus.
At least this is the system that Greek and Roman children used to pick up counting, as shows the etymological meaning of "calculus, calculation" and also the Greek word ψῆφος, pséphos, that means stone and number; for example the Greek expression ψήφους τιθέναι, pséphous tithénai, means to throw the pebbles, to add accounts, to make an account.
Counting or estimating is one of the hardest tasks that human beings learn during their childhood. Humans find some difficulties to count. At first we are only able to identify with a single glance sets of no more than one, two, three or four objects, but from five onwards we are forced to count to know the number.
In the beginning we learn to count using the fingers of our hand and also with pebbles as we have already mentioned or with other systems of such primitive features like, for example, the rope with knots in which each of these are equivalent to the unit.
Curiously this limitation of only immediately identify up to four units is reflected in the languages and so evident in Latin, the language of the Romans from which derive, among others, the Castilian or Spanish language.
This limitation is reflected, for example, in the use of the figures or the writing of the different numbers: The Romans represented the numbers with letters and contrary to what some believe they could only be replicated four times and not more (other day we will discuss the way or system to represent the numbers in Latin and Greek). That is, the "4" was represented with four sticks or four letters "i" ("IIII") precisely because they can be appreciated with a single glance; but for the "5" they used "V".
The indicated limitation is also reflected in the fact that the first three numbers (unus (one), duo (two), tres (three); because quattuor (four) had a special phonetic evolution), are declined, i.e. they have different endings, which do not exist from 5 anymore.
It´s also reflected in the names of the months. The Roman year originally had ten months and it began in March; the first four months had special names: martius, aprilis, maius, iunius; the following were called with the numeral quinctilis, sextilis, september, october, november and december.
Still more curious is this reflection in the name of the people. Only male members of a family had a praenomen and nomen, equivalent to our first and surname or family name; women only carried the last name or family name, so that every woman of the Julia family were called "Iulia".
Well, in a Roman family there were children who were called "Quintus" (Fifth), as Quintus Horatius Flaccus, the famous poet; and "Sextus" (Sixth), as Sextus Julius Frontinus, who wrote a treatise on water and aqueducts; and “Septimius” (Seventh), as the emperor Lucius Septimius Severus who was in power during the years 193-211; and “Octavius” (Eighth) as Caius Octavius Turinus, named after Octavius Caesar Augustus; and “Decimus” (Tenth) as the famous satirist Decimus Iunius Iuvenalis; one was even named "Numerous" as Numerius Iulius Caesar, senator from the Julia family who lived between the third and second centuries BC.
But there were no children who were called "Primus” (First), and they were really few those who were called “Secundus” (Second), Tertius (Third), Quartus (Fourth); these had their own name; so it is from the next when it was necessary to count, so that they were left with the number as their name.
Very curious, indeed; it seems as if in the Latin language had fossilized a primitive limitation in the counting thing, limitation otherwise that had already been completely superseded or forgotten a long time ago.