Abstract: Thales (1), by measuring the height of the inaccessible pyramid and the distance of the unreachable ship far from the port, demonstrates (1a) that anything that can be reported on a plane can be measured; Euclid (2) with the Theorem of the infinity of prime numbers proved that, however large the measure, a number n, there always exists a prime number greater than n and it has been proved that prime numbers are infinite; Gauss (3) with the Fundamental Theorem of Arithmetic (4) (hereinafter T.F.A.) proved that every natural number greater than 1 is either a prime number or can be expressed as a product of prime numbers. Goldbach's conjecture (5) states that the infinite natural numbers are the sum of only two or three numbers among the infinite primes and can be measured on the plane with the triangles of Viviani's Theorem (6) where the sum of two points of the xn + yn plane, shown on the abscissa and ordinate of the plane, are the distances of the infinite natural numbers from the sides of the triangle of Viviani's theorem (6a).