Quotable Mathematics

"[a set is] an embodiment of the idea or concept which we conceive when we regard the arrangement of its parts as a matter of indiffere...

"One very important genus of complex ideas that we encounter everywhere are those in which the idea of collection (Inbegriff ) appears....

"[...] from that circumstance alone we are not allowed to conclude that both sets, if they are infinite, are equal to each other with r...

"In a metamathematical sense our theory provides general concepts applicable to all branches of abstract mathematics, and so contribute...