...an incorrect theory, even if it cannot be inhibited by any contradiction that would refute it, is none the less incorrect, just as a criminal policy is none the less criminal even if it cannot be inhibited by any court that would curb it.
Beyond the natural numbers, addition, multiplication, and mathematical induction are intuitively clear.
One cannot inquire into the foundations and nature of mathematics without delving into the question of the operations by which the mathematical activity of the mind is conducted. If one failed to take that into account, then one would be left studying only the language in which mathematics is represented rather than the essence of mathematics.
Mathematics is nothing more, nothing less, than the exact part of our thinking.
The construction itself is an art, its application to the world an evil parasite.