Speaking of Professor Geach's belief that pronouns in natural language function like the bound variables in quantification theory, Gareth Evans, in ‘Pronouns, Quantifiers, and Relative Clauses - I’ (Canadian Journal of Philosophy 7 [1977] 467-536) says (470):

I want to try to show that there are pronouns with quantifier antecedents that function in a quite different way. Such pronouns typically stand in a different grammatical relation to their antecedents, and; in contrast with bound pronouns, must be assigned a reference, so that their most immediate sentential contexts can always be assigned a truth value. The relevant grammatical relation appears to be Klima's relation of ‘in construction with’. When the pronoun is in construction with its antecedent, as in (4) [‘Some man loves his mother’] and (5) [‘No man is happy when he is in love’] the result is a bound pronoun.