But I'm not "poo-pooing" Kleitman's book! It's just that after reading the beginning I did not find it very engaging personally. It starts with numbers, and p

But I'm not "poo-pooing" Kleitman's book! It's just that after reading the beginning I did not find it very engaging personally. It starts with numbers, and properties of real and complex numbers. The definite integral is not defined until half the book (while it is a simpler concept than the derivative). I prefer to start with calculus, and the relationship between integrals and derivatives right away. And then, much later, when you need some crucial property of real numbers, introduce it as required. You can do a great deal of calculus without needing to know the definition of real number!