The Circle of Zero by Stanley G. Weinbaum

'Look here,' I said at a later time to de Neant. 'If the past and future are the same thing, then the future's as unchangeable as the past. How, then, can we expect to change it by recovering our money?'

'Change it?' he snorted. 'How do you know we're changing it? How do you know that this same thing wasn't done by that Jack Anders and de Neant back on the other side of eternity? I say it was!'