This seems to muddle cardinality. First he defines cardinality as "number of elements" and notes that infinite sets have infinite cardinality, but doesn't expl

This seems to muddle cardinality. First he defines cardinality as "number of elements" and notes that infinite sets have infinite cardinality, but doesn't explain what that might mean. Then he introduces "same cardinality" as a new definition instead of letting it arise out of sameness of number. And next, without any new definition, starts referring to larger cardinality.