“…the expenditure in question, although on suits that were worn only at work, had two purposes inextricably intermingled and not severable by any apportionment the court could undertake.”
“Where a person…negligently (a) delivers any incorrect return… he shall be liable to a penalty [of the difference between the tax actually payable and the tax which would have been payable on the basis of his return].”
“Negligence is the omission to do something which a reasonable man, guided upon those considerations which ordinarily regulate the conduct of human affairs, would do, or doing something which a prudent and reasonable man would not do.”