What is the law on what a trial judge must tell the jury about the evidence, the theories of the Crown and the defence?

47 The classic statement of the law with respect to what the trial judge must tell the jury about the evidence, the theories of the Crown and the defence and the relation of the evidence to those theories is found in Azoulay v. The Queen, 1952 CanLII 4 (SCC), [1952] 2 S.C.R.495 at 497-98 where Taschereau J. in delivering the majority judgment said: The rule which has been laid down, and consistently followed is that in a jury trial the presiding Judge must, except in rare cases where it would be needless to do so, review the substantial parts of the evidence, and give the jury the theory of the defence, so that they may appreciate the value and effect of that evidence, and how the law is to be applied to the facts as they find them. [Emphasis added]