> Kiselev’s child reader is being treated as a participant in mathematics, not as a recipient of facts.

Not sure how the other makes this claim when the passage he himself cites is just another clever proof in the list of clever things that maths books throw at you:

> It is easy to convince oneself that there exist infinitely many prime numbers. Indeed, suppose the contrary, that the number of primes is finite. Then there must exist a greatest prime; let it be a. To refute this assumption, imagine the new number N formed by the rule N = (2·3·5·7···a) + 1, that is, the product of all the primes up to a, plus one… The first term is divisible by every number in the list 2, 3, 5, …, a, while the second (the unit) is not divisible by any of them. Hence there is no greatest prime, and so the sequence of primes is infinite.