He tries to remember that conversation in full, but so much has happened. After a moment, he shakes his head.

'Monseigneur Myriel gave Valjean the silver after he stole it. That is what I recall. I cannot remember what Valjean felt about it, other than his claim that it turned him to good. Except he also stole from a Savoyard, so I do not know what was going through his brain.'

He can accept that Valjean became good because he has seen the proof with his own eyes. The man's actual thoughts about why, and how he could accept such kindness, are still a mystery to Javert. He still cannot comprehend people choosing to commit crime on a physical level at all. Giving a reason for stealing is not the same as explaining how to follow through in action.