Pure set theory deals exclusively with sets, so the only sets under consideration are those whose members are also sets. The theory of the hereditarily-finitesets, namely those finite sets whose elements are also finite sets, the elements of which are also finite, and so on, is formally equivalent to arithmetic. So, the essence of set theory is the study of infinite sets, and therefore it can be defined as the mathematical theory of the actual—as opposed to potential—infinite.” …show more content…
Two people that spoke out against his teaching were his idols Henri Poincare and Leopold Kronecker. With Kronecker even go as far as to public opposition and personal attacks, saying that Cantor was “renegade” along with becoming a “corrupter of youth.” These thoughts is because Kronecker believes that algebraic numbers are countable, and that were numbers that are transcendental are uncountable. Around this time in 1884, Cantor would face depression for the first time until the end of his life. Even thru his fight with depression, Cantor would attend the first International Congress of Mathematicians in 1897. Here Cantor would relight his friendship with Dedekind. Cantor would become ill in 1905 after returning home from the hospital he would write much religious work even saying that God gave him the set theory. Cantor would deal with health problems again in 1909, but Cantor would not retire till the year 1913 at the age of 68. “In June 1917 he entered a sanatorium for the last time and continually wrote to his wife asking to be allowed to go home. He died of a heart attack.” (O’Connor and