Mathematics is logic. Logic is mathematics. The essence of mathematics is logic not numbers. I like the branches of mathematics that do not involve numbers. According to some open minded progressive mathematicians, such as Bertrand Russell and Cassius Jackson Keyser, mathematics is to think the thinkable. Mathematics is to think rigorously whatever is so thinkable and make any topic rigorously thinkable. Consult the book "Human Worth of Rigorous Thinking" by Cassius Keyser. Yes, the essence of mathematics lies in its freedom, said George Cantor. I also recommend many books by Bertrand Russell. Of course, he won the Nobel Literature Price in 1950 for Promoting the Freedom of Thought.