Under section 21 the applicant must adduce evidence that will satisfy the judge that he complies with the conditions. We all know how things can be proved and no necessity exists for making special provision here in regard to that. The judge knows the laws of evidence. One effective means of proof would be to call the man before him; or, if that were not possible, the man's knowledge of English or French could be established by the evidence of those who have talked with him in either English or French. The fact of his knowledge would be proven like any other fact.