Peano reads ‘A ⊃x,y,… B’ as saying ‘whatever x,y,…  may be, from the proposition A one deduces B’ and ‘=’ is Peano's biconditional, that he defines in the usual way from the conditional and conjunction. But he provides us with no more interpretation than that. He refers to variables as ‘indeterminate objects’, but does not discuss what this or what a proposition (or propositional function) that contains propositional objects might be.