'Taught himself? That is very impressive. I think he must be a genius.'

This is entirely truthful. Valjean once tried to teach himself English from a book, out of some idea that he might go to England one day. But he could not manage it; it was before Cosette, and he could never make himself believe that he would ever actually leave France. Looking back, he does not know what all those travel books were for.

'He may enjoy working with his hands. It is hard to know unless he tries it, but I have no doubt he can turn himself to anything.'

Valjean can imagine Marius focusing very hard to learn. Whether he would have the earth in his bones, he cannot guess, but why should he not?

'I expect he would like growing things for you.'