I really hate that phrase "from whatever source derived". I believe it is meant to purport something that just is not so to the common folks. To the lay person they take it as "all that comes in". However that is just not the case. The SCOTUS made that fairly clear in the decisions regarding the 16th in the years after its purported ratification.

I believe the "sources" referenced are those deriving from GovCo sponsored activities, privileges, and things within the scope of taxing. However with the advent of corporate currency (FRN's) GovCo hit the jackpot by going around the restrictions of direct taxation by "loaning" FR credit/notes secured by good assets (your paycheck). This process started in 1933 with the removal of gold and the banking act, was solidified by the SSA act, war taxes of WW2, withholding at source, the removal of silver, and finally the removal of greenbacks in '71.

In hind sight it becomes clear. Nip it in the bud, make your demand early and often.

Some saw what was coming: http://www.archive.org/details/usmon...rpor00crozgoog