"The object and meaning of the rule is this: that as, by reason of the complexity and difficulty of our law, litigation can only be properly conducted by professional men, it is absolutely necessary that a man, in order to prosecute his rights or defend himself from an improper claim, should have recourse to the assistance of professional lawyers, and it being so absolutely necessary, it is equally necessary to use a vulgar phrase, that he should be able to make a clean breast of it to the gentleman whom he consults with a view to the prosecution of his claim, or the substantiating his defence against the claim of others; that he should be able to place unrestricted and unbounded confidence in the professional agent, and that the communications he so makes to him should be kept secret, unless with his consent (for it is his privilege, and not the privilege of the confidential agent) that he should be enabled properly to conduct his litigation. That is the meaning of the rule."