In Collier's on Bankruptcy, 14th edition, Section 5.03, p. 693 it is said that the introduction of the "entity" theory of the firm, coupled with the refusal of the courts to apply it with rigorous logic to all problems * * * "has made this one of the most confusing branches of the law of bankruptcy". However, any confusion as to the law on the subject, at least in the Ninth Circuit, is dispelled by the principles clearly set forth in the opinion of Chief Judge William Denman in Mason v. Mitchell, 9 Cir., 1943, 135 F.2d 599, 602. The following language in the concluding paragraph of this opinion leaves no room for discussion: