ABSTRACT
Set theory is not just one of the main tools in mathematics, it is the very root of mathematics, from which all mathematical disciplines stem. The great German mathematician, Georg Ferdinand Cantor, is considered to be a sole founder of set theory in a series of papers, the first of which appeared in 1874. Although Czech Bernard Bolzano (1781-1848) made one of the first attempts to formalize set theory, in particular in his Paradoxien des Unendlichen 1851 work, by considering the one-to-one correspondence between two sets (later on developed by Cantor to what we now know as cardinals), neither he, nor anyone else, was really a predecessor to Cantor's creation. Ernst Zermelo (1871-1953) was another German, who among his numerous contributions to set theory, is the author of the first axiom for set theory (of 1908) and undoubtedly the primary axiom of the whole mathematics.
